On the top, you take both bases and exponents and put them on the denominator, which changes the exponents to positive. You then apply the exponent outside of the parentheses to 3, m^2, and t, changing them to 27m^6t^3. Then combine the like terms, combining m6 and m5 into m11, and combining t2 and t3 into t5. The remaining answer should be 1/27m^11t^5