Bài 3:
a: 1/6+5/8=8/48+30/48=38/48=19/24
b: 1/16+2/20=5/80+8/80=13/80
c: 2/3+5/18+1/2=12/18+5/18+6/18=23/18
d: 4/5+2/3+1/9=36/45+30/45+5/45=71/45
e: 4/8+3/10=1/2+3/10=5/10+3/10=8/10=4/5
f: 3/21+6/42=6/42+6/42=12/42=2/7
g: 5/15+4/9+2=1/3+4/9+2=3/9+4/9+18/9=25/9
