The solution for the problem follows:
Expense = variable expenses * quantity of produced + fixed expenses
= 14q + 78,490
= 14 (3500) + 78, 490
= 49000 + 78,490
= $127, 490 is the total expense for 3,500 tennis rackets
Get the per piece expense by dividing 127,490 to 3500
Expense per piece = 127,490 / 3500
= $36.43