Jake made a total of 7 copies at a copy shop, with some being black-and-white copies and some being color copies. Black-and-white copies cost 8 cents, and color copies cost 15 cents. If Jake spent a total of 70 cents on copies, which system of equations can be used to determine the number of black-and-white copies and the number of color copies he made? Assume b is the number of black-and-white copies and c is the number of color copies. B c = 7. 8 b 15 c = 70. B c = 7. 15 b 8 c = 70. B c = 70. 8 b 15 c = 7. B c = 70. 15 b 8 c = 7.