3 radical(18) / 9 radical(8)

radical(18) = radical(2*9)
radical(8) = radical(2*4)

3 radical (2*9) / 9 radical(2*4)

3 * 2 radical(9) / 9*2 radical(4)

3 * 2 * 3 / 9 * 2 * 2 = 1/2