7. Вычисли: 35 + 8 - 23 74 + 7 - 31 50 - (34 + 9) 50 - 34 - 9 8 + 6 + 12 + 4 9 + 7 + 13 + 11

Решение: \[35 + 8 - 23 = 43 - 23 = 20\] \[74 + 7 - 31 = 81 - 31 = 50\] \[50 - (34 + 9) = 50 - 43 = 7\] \[50 - 34 - 9 = 16 - 9 = 7\] \[8 + 6 + 12 + 4 = 14 + 12 + 4 = 26 + 4 = 30\] \[9 + 7 + 13 + 11 = 16 + 13 + 11 = 29 + 11 = 40\]