To volume of a rectangular prism is:
[tex]V=lwh[/tex]
where V=volume, l = length, w = width, and h = height.
You're given V=105cm^3, l=7cm, and h=5cm. Plug those numbers into the equation and solve for w:
[tex]V=lwh[/tex]
[tex]105 = (7)(5)w[/tex]
[tex]w=3[/tex]
The width is 3 cm.
