Answer:
W = 9 inches.
Step-by-step explanation:
The volume of a rectangular prism is given by

Where
w,h and l re width, height and length of rectangular prism
It is not mentioned that a box has a length of 18 inches and a height of 3 inches.
Using above formula.

So, the width of the box is 9 inches.
9(-4)-3
-36-3
-39
Your answer is -39
Her home to workplace: 14*5= 70 miles
Her workplace to home: 14*5= 70 miles
Total: 70+70= 140 miles