[ a⁵ (a²b³)⁵ ] / [ a²b⁻² ]
[ a⁵ (a¹⁰b¹⁵) ] / [ a²b⁻² ]
[ a⁵⁰ b⁷⁵ ] / [ a²b⁻² ]
I think this: a⁴⁸b⁷⁷ is the answer.
Hope this helps :)