6^(a+b) = 12 * 18 = 6^3 => a + b = 3 Notice that 3/2 = 18/12 = 3^(a - b) / 2^(a - b) = (3/2)^(a - b) => a - b = 1 Thus, adding the equations a + b = 3 and a - b = 1, we get 2a = 4, or a = 2. This also tells us that b = 1. Thus, a = 2 and b = 1, so (a + b)^(ab) = 3^2 = 9.