w children were riding on the bus. At the bus stop x children got on the bus while some got off the bus. Then there were y children altogether on the bus. How many more children got on the bus than those that got off?
There were w children on the bus to start. 

x children got on the bus. 

y children were on the bus altogether. 

That means that some children must have gotten off the bus. 

We can find out how many children got off the bus by subtracting the total number of children on the bus (y) from the original number of children on the bus (w). 

y - w = the number of children who got off the bus

Now we have the number of children who got on the bus (x) and the number of children who got off the bus (y - w). 

To find out how many more children got on the bus than those that got off, we simply subtract the number of children who got off the bus (y - w) from the number of children who got on the bus (x). 

x - (y - w) = the number of more children who got on the bus than those that got off

Therefore, the answer is x - (y - w).