First we add the fractions

so that we get

then get rid of the denominator by multiplying both sides by '12' (since LCM(4, 6) =12)

3(x - 6) >= 2x

3x - 18 >= 2x

and move the variable to one side of the inequality

3x - 2x >= 18

x >= 18

and this is exactly the closed interval [18, +~)