Connect the nine numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 with operation symbols to form an equation, so that the result is 100

Connect the nine numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 with operation symbols to form an equation, so that the result is 100

1+2+3+4+5+6+7+8×9=28+72=100
From place a to place B, it takes 6 hours and 15 minutes for cars and 9 hours and 30 minutes for trucks. The speed ratio of trucks to cars is much higher
What is the speed ratio of a truck to a car
1/(9+30/60):1/(6+15/60)=25/4:19/2=25:38
6 hours 15 minutes = 6.25 hours
9 hours and 30 minutes = 9.5 hours
The speed ratio of truck to car is 1 / 9.5:1 / 6.25 = 6.25:9.5 = 25:38
15 minutes / 4 hours = 25 hours
9 hours 30 minutes = 19 / 2 hours
The speed ratio of truck to car is 2 / 19:4 / 25 = 25 / 38 = 25:38
25:38
6 hours 15 minutes = 6.25 hours
9 hours and 30 minutes = 9.5 hours
The speed ratio is 1 / 9.5:1 / 6.25 = 6.25:9.5 = 25:38
How to calculate 7.2 × 5.8 + 0.72 × 42
7.2×5.8+7.2×4.2
=7.2×(5.8+4.2)
=7.2×10
=72
7.2*(5.8+4.2)
7.2×5.8+0.72×42
=10 × 0.72 × 5.8 + 0.72 × 10 × 4.2 / / split 7.2 and 42 into 0.72 × 10 and 4.2 × 10
=0.72 × 10 × (5.8 + 4.2) / / extract common factor 0.72 × 10
=7.2×10
=72
0.72*(10*5.8+42)=0.72*100=72
1)7.2×5.8+0.72×42 2)7.2×5.8+0.72×42
=7.2×5.8+7.2×4.2 =0.72×58+0.72×42
=7.2×(5.8+4.2) =0.72×(58+42)
=7.2×10 =0.72×100
=72... Unfold
1)7.2×5.8+0.72×42 2)7.2×5.8+0.72×42
=7.2×5.8+7.2×4.2 =0.72×58+0.72×42
=7.2×(5.8+4.2) =0.72×(58+42)
=7.2×10 =0.72×100
=72 =72
The main method is as follows: multiplication of two numbers, a number reduced (expanded) several times, then the other number will be expanded (reduced) the same multiple, the results are equal. Put it away
Add appropriate operation symbols in the appropriate position of the following formula to make the equation hold. (1) 88888888 = 1000 (2) 44444 = 16 (3) 987654321 = 22
①888+88+8+8+8=1000；②4×4+（4-4）×4=16；③9+8+7+6-5-4+3-2÷1=22．
A car goes from a to B at a speed of 45 kilometers per hour. Three hours later, a car goes from a to B at a speed of 75 kilometers per hour
The car can catch up with the truck a few hours after it leaves
Pursuit problem
Find the distance difference = 45 * 3 = 135km,
So the catch-up time is 135 / (75-45) = 135 / 30 = 4.5 hours
The truck has left: 45x3 = 135 km
Still need: 135 ÷ (75-45) = 4.5 hours
The car can catch up with the truck 4.5 hours after it leaves
Simple calculation of 36 * 2 / 7 * 5 / 72 * 42
=(36*5/72)*(2/7*42)
=5/2*12
=30
36*2/7*5/72*42
=（72＊5＊42）/（7＊72）
=5＊6
=30
Add appropriate operation symbols in the appropriate position of the following formula to make the equation hold. (1) 88888888 = 1000 (2) 44444 = 16 (3) 987654321 = 22
①888+88+8+8+8=1000；②4×4+（4-4）×4=16；③9+8+7+6-5-4+3-2÷1=22．
At 6 a.m., a truck drove from place a to place B at the speed of 50 km / h. three hours later, a bus started from place a to place B at the speed of 75 km / h
When the bus arrives at B, the truck is 25 kilometers away from B. when did the bus arrive at B?
The time of arrival should be 16:00 (4:00 p.m.)
Assuming that the course takes x hours in total, the whole course length is calculated by the speed of the bus: 75X, because the train runs 3 hours more than the bus, and the whole course length is calculated by the speed of the truck: 50 (x + 3) + 25
So: 75X = 50 (x + 3) + 25
X=7
The bus started at 9 a.m. and it took 7 hours. The arrival time should be 16 p.m. (4 p.m.)
Let the distance between a and B be X
In the three hours from 6:00 to 9:00 in the morning, the truck traveled 3 * 50 = 150 km
After 9 a.m., the bus leaves and it takes X / 75 hours to get to B. during this time, the truck has traveled 50 * x / 75 = 2x / 3 km
Now the truck is 25 kilometers away from B, that is to say
150 + 2X/3 + 25 = X
X = 525 km
Therefore, the time for the bus to arrive at place B is:
16 points + 9 points
Let the distance between a and B be X
In the three hours from 6:00 to 9:00 in the morning, the truck traveled 3 * 50 = 150 km
It takes a total of 3 / 75 hours for the bus to arrive at the destination in the morning
Now the truck is 25 kilometers away from B, that is to say
150 + 2X/3 + 25 = X
X = 525 km
Therefore, the time for the bus to arrive at place B is:
9 points + X / 75 = 16 points
How to calculate simply? The first question is 7.2 × 5.8 + 0.72 × 42, the second question is 9.76 × 0.72-0.76 × 0.72 + 0.72, and the third question is 27 × 3.7 + 3.7 × 75
0.72*58+0.72*42=0.72*（58+42）=0.72*100=72
0.72*（9.76-0.76+1）=0.72*10=7.2
3.7*（27+75）=3.7*（100+2）=370+7.4=377.4
Connect the nine numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 with operation symbols to form an equation, so that the result is 100
1+2+3+4+5+6+7+8×9=28+72=100