Party A and Party B face each other from a and B. they meet 4 hours later and continue to move forward. 3 hours later, Party A arrives at B, and Party B is 70 kilometers away from A. find the distance between a and B

Party A and Party B face each other from a and B. they meet 4 hours later and continue to move forward. 3 hours later, Party A arrives at B, and Party B is 70 kilometers away from A. find the distance between a and B

Let a's speed per hour be x km, B's speed per hour be y km, then the distance between AB and ab is 7x. From the title, we know that 7Y + 70 = 7x, 4x + 4Y = 7x, then we get x = 40, y = 30, then the distance between ab and ab is 280 km

1. A barrel of oil, the first time to eat a quarter, the second time to eat a fifth, the first time to eat 4 kg more than the second
1. A barrel of oil, the first time to eat a quarter, the second time to eat a fifth, the first time to eat 4 kg more than the second time. How many kg of this barrel of oil?
2. In the first ten days of August, 400000 tons of steel were produced, 350000 tons in the middle ten days, and 3 / 8 of the whole month in the last ten days?
3. There are 54 students in a class, of which the number of boys is equivalent to 4 / 5 of the number of girls. How many boys and girls are there in this class?

1, 4/（1/4-1/5）=80
2, x/（40+35+x）=3/8 x=45
3. If there are 4 boys and 5 girls, then the number of boys is 54 * (4 / (4 + 5)) = 24. Similarly, the number of girls is 30. In this way, the number of boys is 54 * (4 / (4 + 5)) = 24