a)
7/16-11/42-9/16+7/42=
=7/16-9/16-11/42+7/42=
=-2/16-4/42=-1/8-2/21=(-21-16)/168=-37/168
b)-3 5/11+1 3/8 +2 5/6 - 4 6/11=
=-38/11+11/8+17/6-50/11=
=-38/11-50/11+11/8+17/6=
=-88/11+(33+68)/24=
=-8+101/24=
=(-192+101)/24=-91/24
c)-1,23+2,14+7,38-5,77+1,62=
=-1,23-5,77+7,38+1,62+2,14=
=-7+9+2,14=2+2,14=4,14
d) -9,39+0,74+10,61+3,26+6,25=
= -9,39+4+6,25+10,61=
= -9,39+10,25+10,61=
= -9,39+20,86=
=11,47
