Answer :
w * (w + 12) = 448
w^2 + 12w - 448 = 0
(w-16)(w+28) = 0
w - 16 = 0; w = 16
w + 28= 0; w = -28
dimension can not be negative so answer w = 16
h = w + 12 = 16 + 12 = 28
double check
16x28 = 448
answer
dimensions: 16 and 28
w^2 + 12w - 448 = 0
(w-16)(w+28) = 0
w - 16 = 0; w = 16
w + 28= 0; w = -28
dimension can not be negative so answer w = 16
h = w + 12 = 16 + 12 = 28
double check
16x28 = 448
answer
dimensions: 16 and 28