Answer
$-20m^2c^4$
Work Step by Step
We start with the given expression: $(5c^{-4})(-4m^2c^8)$
We rearrange and regroup the expression using the associative and commutative properties of multiplication: $(5\times-4)(c^{-4}c^8)(m^2)$
We multiply the constants: $-20m^2(c^{-4}c^8)$
To multiply powers with the same base, we add the exponents: $-20m^2c^{8-4}=-20m^2c^4$
