Multiply both sides by 12 to clear out the fractions. Then add 3 to both sides and divide by 4 to fully isolate x.
The steps are shown here:
x/3 - 1/4 = -2/3
12(x/3 - 1/4) = 12(-2/3)
12(x/3) + 12(-1/4) = 12(-2/3)
4x - 3 = -8
4x = -8+3
4x = -5
x = -5/4 is the final answer
