Răspuns:
1)a) -1/2-1/4+2/5+1/-20=-1/2-1/4+2/5-1/20=-10-5+8-1/20=-8/20=-2/5
b) 1/25-1/10+(-5/2)=2-5-125/50=-128/+50=-64/+25
c) -1/+2+(-1/+3-1/6)+((-2/+3)+1/6)=-1/2+(-1/2)+(-+2/+3++1/+6)=-1/2+(-1/2)+(-1/2)=-3/2
2) a) -3/5+5/6=-18+25/30=7/30
b)-2/3-3/4=-+8+9/12=-+17/12
c) 5/6+3/8=20+9/24=29/24
d)28-54/63=-26/+63
