6/7+2/3+1/3
=6/7+(2/3+1/3)
=6/7+1
=13/7
9/4-(3/4+2/3)
=9/4-3/4-2/3
=9/6-6/9
=3/9
=1/3
6/7+2/3+1/3=6/7+(2/3+1/3)=6/7+1=13/7
9/4-(3/4+2/3)= 9/4-3/4-2/3=6/4-2/3=3/2-2/3=9/6-4/6=5/6
6/7+2/3+1/3
=6/7+(2/3+1/3)
=6/7+1
=1又6/7
9/4-(3/4+2/3)
=9/4-3/4-2/3
=3/2-2/3
=5/6