1-qt container of milk cost $0.98 a 1 gal container cost $2.39 which is the better buy

Consider this expression and the steps to evaluate it. 4^5(−2)^9/4^8(−2)^3 1. apply the quotient of powers:      (−2)^a/4^b 2. evaluate powers:           c/d select the value of each variable. a = _ b = _ c = _ d = _