Question 4801
Let the number of sets Aaron sold = x
Let the number of sets Bob sold = 450-x
If Bob sold 5 times as many as Aaron then
450-x=5x

consoldate like terms by adding x to both sides:
450-x+x=5x+x

450=6x

Divide both sides by six to isolate the variable
75=x

So Bob sold 75 sets of windshield wipers and Aaron sold
450-75 = 375
and 375 is 5 times 75, so this is correct.