Problem $2\mathrm{.}25$ from the text. Assume that part A must pass through machines $1$ and $2$ to be completed. For example, machine $1$ drills a hole and machine $2$ puts a taper in the hole made at machine $1.$ Similarly, part B must pass through both machines $3$ and $4$ to be completed. Then parts A and B are comDetermine an equation for the required input for both machines $1$ and $3($not just machine $1$ as stated in the problem.$)$

bined to make a part C at station $5.$