8. Вычисли удобным способом: 37 + 7 + 3; 9 + 7 + 3; 26 + 4; 37 + 13 + 7; 11 + 16 + 4 + 9.

37 + 7 + 3 = 37 + (7 + 3) = 47;

9 + 7 + 3 = 9 + (7 + 3) = 19;

26 + 4 = 30;

37 + 13 + 7 = (37 + 13) + 7 = 57;

11 + 16 + 4 + 9 = (11 + 9) + (16 + 4) = 40.