Please Help! Give full description on how you did both pls. Giving brainleist.

Answer:
7. m^21n^27
8. a^21b^28
Step-by-step explanation:
7. since m^7 raised to the 3rd power = m^( 7 * 3 ) = m^21
then n^9 raised to the 3rd power = n^( 9 * 3 ) = n^27
your answer is m^21n^27
8. a^3 raised to the 7th power = a( 3 * 7 ) = a^21
b^4 raised to the 7th power = b( 4 * 7 ) = b^28
your answer is a^21b^28
hope this helps:)