A$)$ Would it help to have $100$ more units of capacity at plant $1?(2$ points$)$ Why? $(4$ points$)$

There are at least two ways to approach this problem. The most obvious is to increase the capacity of plant $1$ by $100$ and then run Solver to see if the total cost is decreased at all. If it helps to increase the capacity, you need to explain what changes in your shipping plan occurred once the extra capacity is in place. For example, a costly route that was used before the change may no longer be optimal and could be replaced by a lower cost route.