A retail clothing store offers customers an opportunity to open up a credit card during checkout. one location of the retail clothing store states that the number of credit cards, a, that are openedt months since january can be modeled by the function a(t) = 10 2t. the number of credit cards opened at another location, b, is defined by the function b(t) = 25 − t. what is an expression that can be used to determine the total amount of credit cards opened at the two locations? (a b)(t) = 35 t (a b)(t) = 35 3t (a − b)(t) = −15 t (a − b)(t) = −15 3t