The volume of a rectangular prism can be obtained using the formula
[tex]V=l\cdot w\cdot h[/tex]the volume for the first box is
[tex]\begin{gathered} V=10\cdot2\cdot h \\ V=20h \end{gathered}[/tex]the volume for the second box is
[tex]V=5\cdot w\cdot h[/tex]if both volumes are equal then both expressions can be equaled
[tex]20\cdot h=5\cdot w\cdot h[/tex]since both boxes have the same height, then h is equal on both sides and can be cancelled out.
[tex]20=5w[/tex]solve the expression for w
[tex]\begin{gathered} w=\frac{20}{5} \\ w=4 \end{gathered}[/tex]the width of the second box should be 4 feet in order for them to have the same volume.