х+(х+170+х-120)=1400
3х+50=1400
3х=1400-50
3х=1350
х=1350:3
х=450
Х+(Х+170+Х-120)=1400 Х+Х+170+Х-120=1400 3Х+170-120=1400 3Х+50=1400 3Х=1400-50 3Х=1350 Х=1350:3 Х=450ответ: Х=450
х+(х+170+х-120)=1400
3х+50=1400
3х=1400-50
3х=1350
х=1350:3
х=450
Х+(Х+170+Х-120)=1400
Х+Х+170+Х-120=1400
3Х+170-120=1400
3Х+50=1400
3Х=1400-50
3Х=1350
Х=1350:3
Х=450
ответ: Х=450