1) (m - 3m^1/3)/(m^2/3 -3) = m^1/3 *(m^2/3 - 3) / (m^2/3 - 3 ) = m^1/3
2) (m^1/2 - n^1/2) / (m^1/4 + n^1/4) = (m^1/4 + n^1/4)(m^1/4 - n^1/4) / (m^1/4 + n^1/4) = m^1/4 - n^1/4
3) (x^1/3 - 2x^1/6y^1/6 + y^1/3) / (x^1/2y^1/3 - x^1/3 y^1/2 = (x^1/6 - y^1/6)(x^1/6 - y^1/6) / x^1/3y^1/3(x^1/6 - y^1/6) =(x^1/6 - y^1/6) / x^1/3y^1/3