Science and Mathematics for Engineering 6th Edition by John Bird

Exercise 10

The surface area $A$ of a rectangular prism is given by the formula: $A = 2 ( b h + h l + l b )$
Evaluate $b$ when $A _ { 2 } = 11,750 \mathrm {~mm} ^ { 2 } , \mathrm {~h} = 25 \mathrm {~mm}$ and $1 = 75 \mathrm {~mm}$ .