Answer:
w = 10 in
Step-by-step explanation:
Perimeter is the measure of the length of all sides
48 = 2L + 2w
L = w + 4
^ use substitution
48 = 2(w + 4) + 2w simplify.
48 = 2w + 8 + 2w combine like terms
48 = 4w + 8 then subtract 8 from both sides
40 = 4w then divide by 4 to isolate w
10 = w
