а)(2,75:3 2/3-2 1/3:1,75)*3 2/21=1 29/36
1)2,75:3 2/3=275/100:11/3=75/100=3/4
2)2 1/3:1,75=7/3:175/100=100/75=1 1/3
3)3/4-1 1/3=9/12-16/12=-7/12
4)-7/12*3 2/21=-7/12*65/21=65/36=1 29/36
б)(3,24:9/7-3 1/5:1 1/3):(-0,9)=2/15
1)3,24:9/7=324/100:9/7=252/100=2,52
2)3 1/5:1 1/3=16/5:4/3=12/5=2,4
3)2,52-2,4=0,12
4)0,12/(-0,9)=2/15