Answer:
a. TC = 15Q
Step-by-step explanation:
The cost function must include all the costs incurred by a business. Generally it includes a variable part and a fixed part. In this case, since Jack had no fixed costs, his costs are only variable: labor = $10 per hour
in total, Jack's business shoveled 10 x 14 = 140 walks, since he paid his friends $2,100 in total, the variable cost of shoveling one walk = $2,100 / 140 = $15
that means that last years cost function = $15 x number of walks shoveled, or
TC = 15Q (where Q is the number of walks shoveled)