
all we can really cancel is one of the (x-5) and the "x", is all.
Recall your d = rt, distance = rate * time.
notice, the distance are the same, say it was "d" miles.
and if car A is travelling at a speed of say "r" mph, then B is going at "r+15" mph.

how far is B going? well, r + 15.
21. >
22. Distributive Property