Question 290467

.
{{{(b^-2/b^-5)^-2}}}
First, using exponent rules, make the outer exponent positive:
{{{1/(b^-2/b^-5)^2}}}
Distribute the exponent to terms inside the parenthesis:
{{{1/(b^-4/b^-10)}}}
Make the exponents inside the parenthesis positive:
{{{1/(b^10/b^4)}}}
.
{{{b^4/b^10}}}
.
{{{1/b^6}}}