length (l) = 10 in
width (w) = 3 in
height (h) = x
[tex]\text{surface area} = 2lw + 2wh + 2lh\\
\text{surface area}= 2*10*3 + 2*3x + 2*10x=60+6x+20x=60+20x \\ \\\text{volume}=lwh\\\text{volume}=10*3*x=30x \\ \\ \\ \text{volume}=\text{surface area (given)} \\ 30x=60+26x \\ 30x-26x=60 \\ 4x=60 \\ x=60/4\\x=15 \ in[/tex]
