Sarah is purchasing a shirt that is on sale for 20% off. she knows the function that represents the sale price of her shirt is s(p) = 0.8p, where p is the original price of the shirt. she also knows she has to pay 7% sale's tax on the shirt. the cost of the shirt with tax is c(s) = 1.07s, where s is the sale price of the shirt. determine the composite function that can be used to calculate the final price of sarah's shirt by solving for c[s(p)]. a - c[s(p)] = 0.856p b - c[s(p)] = 0.856sp c - c[s(p)] = 1.87p d - c[s(p)] = 1.87sp