X+1/3=4/3-3/20解:X=4/3-1/3-3/20X=17/20
60x+20=80-9x=31/60
x+1/3=3/4-3/20x+1/3=15/20-3/20x+1/3=3/5x=3/5-1/3x=9/15-5/15x=4/15