Answer:
2444
Step-by-step explanation:
The total cost is the integral of the marginal cost.

The total cost of producing units 144 through 625 is 2444.
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If all you need is a number, a graphing calculator can give you that.
Your answer is D because 10*2 is 20 and 6*2 is 12 so 12 out of the next 20 customers will purchase a sandwich.