a) $\frac{(-2.5)^3}{(-2.5)^{-2}}$ (bottom is to the power of -2, for some reason the 2 is bigger!)
b) $(3^3)$$(3^{-6})$ (3 to the power of -6)
c) $\frac{s^2 t^{-1}}{(s^4t^4)^\frac{1}{2}}$ (t to the power of -1)
how do i simplify and make the exponents positive?
(i didn't have the basic requisites before in order to simplify and make exponents positive)
you should know that : $$a^b*a^c = a^{b+c}$$ and $$\frac{a^b}{a^c} = a^{b-c}$$ So you can simplify exponents, and to write only with positive ones, it might be useful to remember that $a^{-b} = \frac{1}{a^b}$
PS : it is also important to remember that ${(a^b)}^c = a^{b*c}$ and $a^{\frac {1}{2}} = \sqrt a$