`a, 1/3 + 3/4 + 2/3 + 1/4`
`=(1/3 +2/3)+(3/4 +1/4)`
`= 1+1`
`=2`
`b, 3/4 + 3/5 + 2/8 + 4/10`
`= ( 3/4 + 2/8) + (3/5 + 4/10)`
`= ( 6/8 + 2/8)+( 6/10 +4/10)`
`= 1+1`
`=2`
`c,` cái vuông vuông là gì vậy ạ
a: =1/3+2/3+1/4+3/4=1+1=2
b: =3/4+1/4+3/5+2/5=2
c: =(1+2+3+...+9)/10=45/10=9/2