1)2 3/10+(1,5-0,7)=2,3+1,5-0,7=3,1
2)6 3/4-(2,35-0,23)=27/4-2,12=6,75-2,12=4,63
3)3 2/5-(0,9+0,45)=17/5-1,35=3,4-1,35=2,05
4)(12,4-9,35)-2 12/25=3,05-62/25=3,05-2,48=0,57
5)(27,61-8,11)+4 1/20=19,5+81/20=19,5+4,05=23,55
6)(6,35-2,05)+9/10=4,30+0,90=5,20