Answer
a) -64 b) 64 c) -$\frac{27}{25}$
Work Step by Step
Note here that putting parenthesis matters:
a) -2$^6$ = -(2$^6$) = - 64
b) (-2$^6$) = (-2)*(-2)*(-2)*(-2)*(-2)*(-2) = 64
c) ($\frac{1}{5}$)$^{2}$ $\times$ (-3)$^3$ = $\frac{1}{25}$ $\times$ (-27) = -$\frac{27}{25}$