67 + 18 + 3 + 2;
24 + 65 + 5 + 6;
90 − 6;
96 − 10;
53 − (20 + 7);
53 − 20 + 7.
67 + 18 + 3 + 2 = (67 + 3) + (18 + 2) = 70 + 20 = 90;
24 + 65 + 5 + 6 = (24 + 6) + (65 + 5) = 30 + 70 = 100;
90 − 6 = 84;
96 − 10 = 86;
53 − (20 + 7) = 53 − 20 − 7 = 33 − 7 = 26;
53 − 20 + 7 = 33 + 7 = 40.