Hi,
I'll state the problem as {(2/3)*((3/4)x-1/2))}-{(1/2)*((3/4)x-(2/3))} if you multiply each term by the fraction you have
(1/2)x-(1/3)-((3/8)x-(1/3)) now combine like terms and you have
(1/8)x since (1/2)x-(3/8)x =(4/8)x-(3/8)x=(1/8)x
Jim