Ответ:50 + 40 − 20 = 90 − 20 = 70.30 + 60 − 50 = 90 − 50 = 40.90 − 40 + 20 = 50 + 20 = 70.50 + 20 − 30 = 70 − 30 = 40.80 + 20 − 50 = 100 − 50 = 50.40 + 30 + 5 = 70 + 5 = 75.