Question

Вычислить с объяснением. 19+8. 29+8. 18-9. 28-9. 18+9. 28+9. 17-9. 27-9.

Answer 1

Пошаговое объяснение:

19+8 = 19 + (1+7) = (19 + 1) + 7 = 20 + 7 = 27.

29+8 = 29 + (1+7) = (29 + 1) + 7 = 30 + 7 = 37.

18 - 9 = 18 - (8+1) = (18 - 8) - 1 = 10 - 1 = 9.

28-9 = 28 - (8+1) = (28 - 8) - 1 = 20 - 1 = 19.

18 + 9 = 18 + (2 + 7) = (18+2) + 7 = 20 + 7 = 27.

28 + 9 = 28 + (2 + 7) = (28+2) + 7 = 30 + 7 = 37.

17 - 9 = 17 - (7+2) = (17 - 7) - 2 = 10 - 2 = 8.

27 - 9 = 27 - (7+2) = (27 - 7) - 2 = 20 - 2 = 18.