Basically when using exponents, you're multiplying it by itself a certain amount of times. You have to multiply the numerator and denominator by itself 3 times, so it is basically like 2 to the power of the 3 and 3 to the power of three.
[tex] 2^{3} =8
\\ 3^{3} =27
\\ ( \frac{2}{3}) ^{3} = \frac{8}{27} [/tex]
