If the perimeter of a rectangle is 38 inches how tall is it

P = 2l + 2w 
38 = 2l + 2w 
l = w + 3 , (the length is 3 inches more than the width) 

then substitute w + 3 to l in 38 = 2l + 2w 

38 = 2(w + 3) + 2w 

38 = 2w + 6 + 2w 

38 = 4w + 6, then take away 6 from both sides 

32 = 4w, then divide both sides by 4 

w = 8 inches (width)

The percent discount was 120