at the beginning of summer matt could swim 12 laps. at the end of summer he could swim 15 laps. what is the percent gain

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 = _