((9+2)/12)*3+((5-3)6)*9/2=(27+6)/12+9/6=(33+18)/12=51/12=4целых и 1\4
Решение
А*1000=3000
А=3000/1000
А=3
1) = 17(m+n) = 17 • 1000 = 17000;
2) = 9(r + l) = 9 • 12 = 108
1) 10 : 4 - 5 2/5 : 6 = 5/2 - 27/5 : 6 = 5/2 - 27/5×1/6 = 5/2 - 27/30 = 5/2 - 9/10 = 25/10 - 9/10 = 16/10 = 8/5 = 1 3/5 (или = 2,5 - 27/30 = 2,5 - 0,9 = 1,6)
2) (2,3 + 1,9) : 8 = 4,2 : 8 = 0,525