Решите два уравнения: а) а : 3 + 400 = 600 б) (500 - х ) * 6 = 120

а) а : 3 + 400 = 600                             б) (500 - х) * 6 = 120

а : 3 = 600 - 400                                       500 - х = 120 : 6

а : 3 = 200                                                500 - х = 20  

а = 200 * 3                                                х = 500 - 20

а = 600                                                     х = 480

Проверка: 600 : 3 + 400 = 600               Проверка: (500 - 480) * 6 = 120 

                  200 + 400 = 600                                       20 * 6 = 120              

                  600 = 600                                                 120 = 120