This question can be tricky...
So whats given is the Area and how we can find x
Area = 100inch
The length is X inches
and width (x - 15) inches
The way to find the area is to multiply length and width
So in this problem we have to go backward
The value for X is 20 inches
The reason for this is because when you subtract 20 from 15 you get 5
⊂ 20 times 5 is 100 ⊃
Hope this helps!