Question

уравнение (287+x)-109=298

Answer 1

(287 + х ) - 109 = 298
287 + х = 298 + 109
287 + х = 407
х = 407 - 287
х = 120
Проверка :
(287 + 120) - 109 = 298
             407 - 109 = 298
                       298 = 298

Answer 2

(287+х)-109=298
287+х=298+109
287+х=407
х=407-287
х=120.