20 + (42 + 8) + 6 = 20 + 50 + 6 = 70 + 6 = 76;
50 + (34 + 6) + 7 = 50 + 40 + 7 = 90 + 7 = 97;
10 + (35 − 15) = 10 + 20 = 30;
70 − (84 − 40) = 70 − 44 = 26.
Условие:
20 + (42 + 8) + 6;
50 + (34 + 6) + 7;
10 + (35 − 15);
70 − (84 − 40).
20 + (42 + 8) + 6 = 20 + 50 + 6 = 70 + 6 = 76;
50 + (34 + 6) + 7 = 50 + 40 + 7 = 90 + 7 = 97;
10 + (35 − 15) = 10 + 20 = 30;
70 − (84 − 40) = 70 − 44 = 26.