99 − 4 = 95; 30 + 7 = 37; 99 − 90 = 9; 94 − 60 = 34; 95 − 45 = 50; 58 − 20 = 38; 20 + 6 = 26; 40 + 5 = 45; 39 − 20 = 19; 66 − 26 = 40; 50 − 3 = 47; 39 − 30 = 9; 70 + 9 = 79; 58 − 38 = 20; 49 − 39 = 10.