Required board feet
$V = \dfrac{16(150)(2) \, \text{ ft}^2\cdot\text{in}}{1(1)(1) \, \text{ ft}^2\cdot\text{in/board ft.}}$
$V = 4800 \, \text{board ft.}$
Total cost of lumber
$C = \dfrac{\$40}{1000 \, \text{board ft.}} \times 4800 \, \text{board ft.}$
$C = \$192$ answer