Please answer correctly !!!!!!! Will mark brainliest !!!!!!!!!!!!!

Answer:
4^15/ b^21
Step-by-step explanation:
( b^7 / 4^5) ^ -3
b^7 ^ -3 / 4^5^-3
We know that x^y^z = x^ (y*z)
b^ (7*-3) / 4^(5*-3)
b ^ -21 / 4 ^ -15
We know that a^ -b = 1/ a^b
We do not like to leave negative exponents
1 * b^21 * 4 ^15
4^15/ b^21