Hi 64^x=16^(x-1) (2^6)^x = (2^4)^(x-1) 2^6x = 2^4(x-1) 6x = 4(x-1) 2x = -4 x = -2 CHECKING our Answer*** 64^-2 = 16 ^-3 1/4096 = 1/4096