2 1/2 × (2/15- 3 5/6)-2 3/4 ЭТО ПЕРВЫЙ☝ - 1 1/7 ×(4/5+19/20)×(6 5/6+4 2/3 ЭТО ВТОРОЙ☝ (6 3/8-2 3/4)×(-4)+ 7/18×9 ЭТО ТРЕТИЙ ☝ 9 1/6: (4 1/3-8)+24× 3/8 ЭТО ЧЕТВЕРТЫЙ☝

2 1/2 × (2/15- 3 5/6)-2 3/4 2/15-3 5/6= 2/15-23/6=4/30-115/30= -111/30 2 1/2×(-111/30)= -5/4×111/30= -111/24 -111/24-2 3/4= -111/24-11/4= -111/24-66/24= -177/24= -7 9/24= - 7 3/8 - 1 1/7 ×(4/5+19/20)×(6 5/6+4 2/3) 4/5+19/20=16/20+19/20=35/20=7/4 6 5/6+4 2/3=10 (5/6+2/3)= 10(5/6+4/6)= 10(9/6)= 10(3/2)=10+1 1/2=11 1/2=23/2 -8/7×7/4×23/2= -23 (6 3/8-2 3/4)×(-4)+ 7/18×9 6 3/8-2 3/4=4(3/8-6/8)= 4-3/8=3 5/8=29/8 29/8×(-4)= -29/2 7/18×9=7/2 -29/2+7/2= -22/2= -11 9 1/6: (4 1/3-8)+24× 3/8 4 1/3-8= -3 2/3= - 11/3 9 1/6÷(-11/3)=55/6×(-3/11)= -5/2 24×3/8=9 -5/2+9=9- 2 1/2= 6 1/2