Consider a two-part process with an expansion from 3 to $6 \mathrm{ft}^{3}$ at a constant pressure of 20 16f/in $^{2}$ followed by an expansion from 6 to $12 \mathrm{ft}^{3}$ with a linearly rising pressure from $20 \mathrm{lbf} / \mathrm{in}^{2}$ ending at 40 lbf/in'. Show the process in a $P-V$ diagram and find the boundary work.