Решите уравнение: (x+x-20)*4+20=580
(х+х-20)×4+20=580 (2х-20)×4+20=580 8х-80+20=580 8х-60=580 8х=640 х=80
(2х-20)*4+20=580 8х-80+20=580 8х=580-20+80 8х=640/8 х=80