Multiply or divide.
14. (x^5y5/3)2
16. (a^2b^2)(a1/3b1/4)
18. x2/3 divided by x1/3
20. z4/5 divide by z1/2
If those numbers following expressions are exponents, we normally use ^
[x^5y^(5/3)]^2 = x^10 y^(10/3)
or (xy^(1/3))^10
a^2b^2 * a^1/3 b^1/4 = a^7/3 b^9/4
x^2/3 / x^1/3 = x^2/3 * x^-1/3 = x^1/3
z^4/5 / z^1/2 = z^(4/5 - 1/2) = z^3/10