25又3/4 ÷ 1/4 =103/4÷1/4=103
(5/6-3/4)× 4/5+1/3
=4/6-3/5+1/3
=1-3/5
=2/5
3/17 ×1/3 +14\3× 1\17
=1/17×（1+14/3）
=1/3