Question 255033
First of all, it is not an equation. An equation equates something with an equal sign.
It is an expression .
What does 


{{{25^(-3/4)}}}

 mean
The minus sign says to take a reciprocal
so it is really {{{1/25^(3/4)}}}
the 3 of 3/4 says to cube it 

{{{1/(25*25*25)^(1/4)}}}

=

{{{1/((5*5)*(5*5)*(5*5))^(1/4)}}}



{{{1/(5^(4/4)*5^(2/4))}}}


the 4 says to take its fourth root. {{{1/5sqrt(5)}}}


but we try not to leave radicals in the denominator.
So we multiply by {{{sqrt(5)/sqrt(5)}}}
which yields
{{{sqrt(5)/25}}}