Question

Which expression is equivalent to (1st picture is part of the question. Other 4 pictures are answers)

Answer 1

we have that
5(r^6)(t^4){[4(r^3)(s^2)(t^4)]/[2(r^4)(s)(t^6)]}^5
=5(r^6)(t^4){[2s]/[(r)(t^2)]}^5
=5(r^6)(t^4){[32(s^5)]/[(r^5)(t^10)]}
=160(r)(s^5)/(t^6)

the answer is 
160(r)(s^5)/(t^6)