Answer:
A. `1/2` foot
Explanation:
The computation of the width of the box is shown below:
15 ÷ 28 = (5 ÷ 7)(1 1 ÷ 2)(width)
15 ÷ 28 = (5 ÷ 7)(3 ÷ 2)width
15 ÷ 28 = (15 ÷ 14)width
(15 ÷ 28) ÷ (15 ÷ 14) = width
(15 ÷ 28) × (14 ÷ 15) = width
w = 14 ÷ 28
= 1 ÷ 2 ft