Answer
$-5x^{36}$
Work Step by Step
Divide the monomials by cancelling out common factors of the numbers and subtracting the exponents of variables.
$(\frac{-15x^{40}}{3x^4})=-\frac{15}{3}x^{40-4}=-5x^{36}$
Check the answer.
$3x^4(-5x^{36})=-15x^{4+36}=-15x^{40}$
