Primary school mathematics, very simple, help 1. It's a slope road from land a to land B. a truck travels 30 kilometers per hour uphill and 40 kilometers per hour downhill. It takes 7 hours to go back and forth. How many kilometers are there between the two places 2. A car runs 120 kilometers in 2.5 hours and runs from a to B for 6 hours at the same speed. If Xiaoguang rides a bicycle from B to a while the car starts from a, the speed and the speed of the car are 1:4. How long does it take for Qiu Xiaoguang and the car to meet? Team a and team B are digging a 620 meter long canal. Team a is digging 3 / 4 of the canal equal to team B's 4 / 5. How many meters more is team a digging than team B?

Primary school mathematics, very simple, help 1. It's a slope road from land a to land B. a truck travels 30 kilometers per hour uphill and 40 kilometers per hour downhill. It takes 7 hours to go back and forth. How many kilometers are there between the two places 2. A car runs 120 kilometers in 2.5 hours and runs from a to B for 6 hours at the same speed. If Xiaoguang rides a bicycle from B to a while the car starts from a, the speed and the speed of the car are 1:4. How long does it take for Qiu Xiaoguang and the car to meet? Team a and team B are digging a 620 meter long canal. Team a is digging 3 / 4 of the canal equal to team B's 4 / 5. How many meters more is team a digging than team B?

30:40 = 3:4 3 + 4 = 7 (hours) 7 / 7 = 1 3 * 1 = 3 3 * 40 = 120 (km)
A: the distance between a and B is 120 kilometers
120 / 2.5 = 48 (km) 6 * 48 = 288 (km) 288 / (1 + 4) = 57.6 (km)
57.6 * 4 / 48 = 230.4 / 48 = 4.8 (hours)
A: Xiaoguang and this car have been together for 4.8 hours
3 / 4: 4 / 5 = 15:16 15 + 16 = 31 620 / 31 = 20 (m) 16-15 = 120 * 1 = 20 (m)
A: team a dug 20 meters more than team B