Please answer correctly

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

16

step-by-step explanation:

2 x 40 = 80

80/5

= 16

5x+10 is the correct one

hope this