$L= {[{M^{ - 1}}{L^3}{T^{ - 2}}]^x}\,$${[L{T^{ - 1}}]^y}{[M{L^2}{T^{ - 1}}]^z}$
By comparing the power of M, L and T in both sides we get
$ - x + z = 0$, $3x + y + 2z = 1$ and $ - 2x - y - z = 0$
By solving above three equations we get
$x = \frac{1}{2},\,y = - \frac{3}{2},z = \frac{1}{2}$