4. [0/0.77 Points] DETAILS PREVIOUS ANSWERS TAMUBUSCALC1 4.1.014. 3/6 Submissions Used MY NOTES The marginal cost function for Mark Hall's bulk greeting cards is given by C'(x) = 4x 0.7 dollars per box when x boxes of greeting cards are sold. The total cost of making and shipping 15 boxes of cards is $75. Find the company's cost function, in dollars, when x boxes of greeting cards are sold. (Round any numbers to two decimal places if necessary.) C(x) = Submit