A freight car and a passenger car travel from the two places opposite each other. The passenger car takes 8 hours to complete the whole journey. It takes 10 hours for the freight car to complete the whole journey. The freight car starts first and meets each other in 1 hour How many hours did the bus run?

A freight car and a passenger car travel from the two places opposite each other. The passenger car takes 8 hours to complete the whole journey. It takes 10 hours for the freight car to complete the whole journey. The freight car starts first and meets each other in 1 hour How many hours did the bus run?

The bus took x hours
1/8X+1/10X+1/10=1
9/40X=1-1/10
9/40X=9/10
X=4
A: the bus took four hours

A car from a to B, 45 km per hour, 6 / 5 hours to reach. If the speed is increased by 20%, how many hours can it reach?

6 / 5 △ 1 + 20% = 6 / 5 △ 6 / 5 = 1 hour

The total length from a to B is 180 km. A car drives from a to B at the speed of 36 km per hour. After arriving at a, it returns to B at the speed of 45 km per hour
Well, what's the average speed of this car

180*2/(180/36+180/45)
=360/(5+4)
=360/9
=40KM

It takes 5 / 4 hours for a truck at the wholesale station to deliver goods to destination B. It takes only 3 / 2 hours for the truck to return to destination B. the speed of the truck when it returns to destination B is 45 km / h
It takes four fifths of an hour for a truck to deliver goods to destination B. It takes only two-thirds of an hour for the truck to return. What is the speed of the truck when it returns?

I'm in sixth grade, too. That's what I wrote. Right
45×5/4=36（KM）
36 △ 3 / 2 = 54 (km / h)
A: the speed of the truck when it returns is 54 km / h