We'll split this into two parts:
(9y^5)^7 & (86x^5)(65x^3)
(9y^5)^7 is easy. It is just 7 x 5 = 35 so that is 9y^35.
Part two: (86x^5)(65x^3). In other words we are multiplying 65 by 85 and adding 3 and 5. This is therefore 5590x^8. Combine them and we get 9y^35(5590x^8 ) as its simplest form.