## Algebra 1

$b^{20}$
$(b^{-4})^?=b^{20}$ To raise a power to a power, we multiply the exponents. This means that the product of $-4$ and the second exponent must be equal to $20$. This is only true if the second exponent is $-5$ because $-4\times-5=20$ This gives us the equation $(b^{-4})^{-5}=b^{20}$