QA and B are 390 kilometres apart. A train departs from A at 10 a.m. and travels at 65 kmph to B. Another train departs from B at 11 a.m. and proceeds at 35 kmph towards A. When do they get together?

The time at which the two vehicles meet is given as x hours after 10 a.m.

The distance traveled by the first vehicle in x hours is given as 65x km, and the distance traveled by the second vehicle in x-1 hours is given as 35(x-1) km.

The total distance traveled by both vehicles is given as 390 km.

We can set up an equation to represent the relationship between the distance traveled by each vehicle and the time at which they meet. In this case, the equation is (distance traveled by first vehicle in x hours) + (distance traveled by second vehicle in x-1 hours) = total distance traveled.

We can solve for the time at which the vehicles meet by rearranging the equation to isolate the time. 

The equation given is (distance traveled by first vehicle in x hours) + (distance traveled by second vehicle in x-1 hours) = total distance traveled. 

We can solve for x by subtracting (distance traveled by second vehicle in x-1 hours) from both sides of the equation, 

which gives us (distance traveled by first vehicle in x hours) - (distance traveled by second vehicle in x-1 hours) = total distance traveled - (distance traveled by second vehicle in x-1 hours). 

This simplifies to (65x - 35(x-1)) = 390 - 35(x-1). Solving for x gives us x = 17/4.

Since x is the time at which the vehicles meet, given in hours, 

the time at which they meet is 17/4 hours after 10 a.m., or 2.15 p.m.