Ответ:80 : 8 = 10; 640 + 260 = 900; 4 · 9 = 36; 70 · 1 = 70.2 · 9 = 18; 140 − 131 = 9; 430 + 122 = 552; 900 : 10 = 90.97 − 74 = 23; 10 · 40 = 400; 528 : 6 = 88; 63 : 7 = 9.6 · 50 = 300; 50 : 2 = 25; 51 : 3 = 17; 44 − 28 = 16.