A business has customers located in Lubbock, Amarillo, and points in between as follows:

Lubbock $10$ customers

$10$ miles from Lubbock $1$ customer

$25$ miles from Lubbock $3$ customers

$50$ miles from Lubbock $1$ customer

$70$ miles from Lubbock $2$ customers

Amarillo $6$ customers

a$.$ Suppose that a separate trip must be made to each customer and that

transportation costs per mile are the same for all trips to any customer. Where does the business locate to minimize transportation costs?