30%x=120 30x=12000 x=400
x-60%x=160 40%x=160 40x=16000 x=400
120x-20x=40 100x=40 x=0.4
50%x-33%x=34 17%x=34 17x=3400 x=200
x+130%x=460 230%x=460 230x=46000 x=200
x+1/5x=240 6/5x=240 6x=1200 x=200
解:30%x=120. x=400
x-60%x=160, x=400
120x-20x=40, x=0.4
50%x-33%x=34, x=200
x+1/5x=240
6/5x=240
x=200
x-60%x=160
0.4x=160
x=400
50%x-33%x=34
0.17x=34
x=200
120x-20x=40
100x=40
x=0.4
x+130%x=460
2.3x=460
x=200