The system 25^x = 125 * 5^y (1) (4^x) * (8^-y)=1 (2) is equivalent to= (1') = (2') Which in turn is equivalent to 2x = 3 + y (1'') 2x - 3y = 0. (2'') ============> 2x - y = 3 2x - 3y = 0 ------------------------Subtract to get -y - (-3y) = 3 ====> -y + 3y = 3 ====> 2y = 3 ====> y = ====> 2x = = ====> x = . Answer. x = , y = .