The distance between Party A and Party B is 420 kilometers. Two cars drive from Party A to Party B at the same time. The first car runs 42 kilometers per hour, and the second car runs 42 kilometers per hour 28km, the first car to B immediately back and forth, how many hours do two cars share from departure to meet?

The distance between Party A and Party B is 420 kilometers. Two cars drive from Party A to Party B at the same time. The first car runs 42 kilometers per hour, and the second car runs 42 kilometers per hour 28km, the first car to B immediately back and forth, how many hours do two cars share from departure to meet?

Time = 420 × 2 ÷ (42 + 28) = 12

8. The distance between a and B is 420 km. Two cars drive from a to B at the same time. Car a travels 42 km per hour and car B 28 km per hour. Car a arrives at B

A. The distance between B and a is 420 kilometers. Two cars drive from a to B at the same time. Car a travels 42 kilometers per hour and car B 28 kilometers per hour. When car a arrives at B, how far is car B from B?
420-(420÷42)×28
=420-280
=240 (km)
A: when car a arrives at B, car B is 240 kilometers away from B

The distance between Party A and Party B is 420 kilometers. Two cars drive from Party A to Party B at the same time. The first car travels 42 kilometers per hour. It returns to Party B immediately and meets the second car 84 kilometers away. How many kilometers per hour does the second car travel?

Suppose the speed of the second car is x km / h, and the total distance traveled by the first car is 420 + 84 = 504km
The walking distance of the second car is 420-84 = 336km, and the equation is: (420 + 84) / 42 = (420-84) / X
The solution is x = 28
A: the second car is 28 kilometers per hour

The railway between Party A and Party B is 240 km long. A train runs 36 km every three fifths of an hour from Party A to Party B. how small does it take to complete the whole journey

240 (36 / 5) = 4 (hours)

A bus goes from place a to place B, and a train goes from place B to place A. when the truck runs 180 km, the bus runs four seventh of the whole journey. When the bus arrives at place B, the truck runs seven eighth of the whole journey. How many kilometers are there between Party A and Party B?
The transport team delivers a batch of cement. When it delivers 20 tons more than two fifths of the total cement, the rest is 10 tons less than the one transported away. How many tons of this batch of cement in total?

1. The freight car takes 180km, the passenger car takes 4 / 7 of the whole journey, the freight car takes another 180 * 4 / 3, the passenger car completes the whole journey, and the freight car takes 7 / 8 of the whole journey, so the freight car now takes 7 / 8 of the whole journey * [1 / (1 + 3 / 4)] = 1 / 2 = 180km, so the whole journey is 360km
Let a t (2 / 5A + 20) - (3 / 5a-20) = 10 a = 150t

Two trains leave from a and B at the same time. The passenger train runs 60 kilometers per hour from a to B, and the freight train runs from B to A. when they meet, the passenger train can reach B in another 3.2 hours, and the freight train is 288 kilometers away from A. how many kilometers does the freight train travel per hour?

When they met, the bus traveled 288 kilometers
So the meeting time is 288 △ 60 = 4.8 hours
2 × 60 = 192 km
Before meeting, the freight car runs 192 kilometers
192÷4.8=40
A: on average, trucks travel 40 kilometers per hour

The truck drove from city a to city B at the speed of 80km / h, unloaded at City C at 5h, stopped at City C for 1h, accelerated at 20km / h, and then arrived at city B at 4 o'clock?

80*5+（80+20）*4
There is a formula,

Party A and Party B start from place a and go in the same direction by bike. Party A starts first. Half an hour later, Party B catches up with Party A at the speed of 80km / h. If Party B goes for 3.5H, he catches up with Party A
Come on, hurry

Suppose a's speed is x km / h, then when B catches up with a, a's total walking time is (0.5 + 3.5) h, a's total walking distance is 4x km, B's total walking distance is 3.5 × 80 km. According to the equal distance of two people, the equation is: (0.5 + 3.5) x = 3.5 × 804x = 280x = 70, and the formula is: (3.5 × 80) / (0.5 + 3.5) = 2

Someone drives a car from Jiacheng to Yicheng at the speed of 100km / h, takes a rest for 30min after arriving at Yicheng, and then drives at the speed of 80km / h
It takes 5h to return to city a from Yicheng, and find the distance between city a and city B (equations)

Suppose the distance is X
Then divide X by 100
X divided by 80
Total X / 100 + X / 80 + 0.5 = 5

A driver drives his car from a to B. he reaches his destination in 6 hours at an average speed of 70 km / h
(1) What is the relationship between the speed V and the time t when he returns on the same road?
(2) If the driver has to return to Jiadi within 5 hours, what is the return speed?

The distance is 70 × 6 = 420km
one
v=420/t
Or VT = 420
two
420/v84
A: return speed cannot be lower than 84 km / h