Movie tickets cost $6 for adults and $2 for children under the age of 12.If 175 movie tickets were sold with cash receipts of 750,how many children's tickets were sold?(Set up only,do not solve.) What is the equation?A. a+c=750 a+c=175B. a+c=175 6a+2c=750C. a+c=750 6a+2c=175