Answer:
length = 7 inches
Explanation:
height = 10
width = w
length = w + 4
The volume of a box is LxWxH
(w+4)(w)(10) = 10w² + 40w
The volume of the box is 210 in³
10w² + 40w = 210
10w² + 40w - 210 = 0
divide by 10
w² + 4w - 21 = 0
by factoring
(w+7)(w-3) = 0
w1 = -7
w2 = 3
use the positive one, because there is no negative length.
From the given problem, its length is 4 inches more than its width.
length = w + 4
∴ 3 + 4 = 7