Train a leaves a station traveling at 40 miles per hour. four hours later train b leaves the same station traveling in the same direction at 50 miles per hour. how long does it take for train b to catch up to train a? how do you do ?

Since train A is going 40 miles per hour by the time train B leaves it has gone 160 miles. You should keep on adding 50 to itself until you get 160 but you can't get exactly 160, you get 150 so add ten. Since we had to add ten, it won't be an exact number. But it takes 5x10 to get 50 therefore 10 would be 1/5 Then you count up how many hours it took to get to 150 then add 1/5 to that. You should get the answer 3 1/5