C(a)=7500a−1500C, left parenthesis, a, right parenthesis, equals, 7500, a, minus, 1500, M(c) = 0.9c - 50M(c)=0.9c−50M, left parenthesis, c, right parenthesis, equals, 0, point, 9, c, minus, 50, y M(C(a))=6750a-1400M(C(a))=6750a−1400