Те с уравнением: -61+х=-42; 34-х=-18:

- 61 + х = - 42                                 34 - х = - 18

х = - 42 - (- 61)                                х = 34 - (- 18)

х = - 42 + 61                                    х = 34 + 18

х = 61 - 42                                       х = 52

х = 19                                              Проверка:

Проверка:                                       34 - 52 = - 18

- 61 + 19 = - 42