A certain brand of tea bags comes in packages of 5,10, and 20 sachets, costing $5, $9, and $15 per package, repectively. A store sold 16 packages containing a total of 165 sachets and took in $140. a....

A certain brand of tea bags comes  in packages of 5,10, and 20 sachets, costing $5, $9, and $15 per package, repectively.  A store sold 16 packages containing a total of 165 sachets and took in $140.

a. Write a system of equations to match the description of the information give.

b. Determine how many packages of each type were sold using the Inverse Method.