$(20$ points$)$ Use the Excel SOLVER tool to solve the following total cover

problem. Amazon try to increase its distribution centers $($DCs$)$ in Texas in order

to deliver the orders to major cities within $24$ hour time frame. The following

table shows capacity of the distribution centers to the cities. If the coefficient is I,

that distribution center can deliver the order within $24$ hours. Find out the

distribution centers need to be added in order to achieve the one day delivery

goal.