7. 860-800 700+50 999-90 (80-45):5 98-84:7 90-51+9 5⋅9+7⋅6 5⋅9-7⋅6 5⋅(9-7)⋅6

860 - 800 = 60 700 + 50 = 750 999 - 90 = 909 (80 - 45) : 5 = 35 : 5 = 7 98 - 84 : 7 = 98 - 12 = 86 90 - 51 + 9 = 39 + 9 = 48 5 * 9 + 7 * 6 = 45 + 42 = 87 5 * 9 - 7 * 6 = 45 - 42 = 3 5 * (9 - 7) * 6 = 5 * 2 * 6 = 10 * 6 = 60