1)- 21,5+(- 3 4/5)+ (-8 3/20)=-21 5/10-3 4/5- 8 3/20=-21 10/20-3 16/20-8 3/20=
=-32 29/20=- 33 9/20
2)-2 5/8+ (-9,25)+(-3/4)=-2 5/8-9 25/100-6/8=-2 11/8-9 1/4=-3 3/8-9 2/8=-12 5/8
3)-4 9/25+ (-0,62)+(-3 1/5)=-4 9/25-3 5/25-62/100=-7 14/25-62/100=-7 56/100-62/100=-7 118/100=-8 18/100=-8,18