60+х=340+130
60+х=470
х=470-60
х=410
х+240=320+40
х+240=360
х=360-240
х=120
140+х=650-120
140+х=530
х=530-140
х=390
400+х=850
х=850-400
х=450
х+880=1000-100
х+880=900
х=900-880
х=20
700-х=120+280
700-х=400
х=700-400
х=300
x-540=480-330
х-540=150
х=150+540
х=690
x-510=230
х=230+510
х=740
880-x=400-230
880-х=170
х=880-170
х=710
650-x=225+125
650-х=350
х=650-350
х=300