12又5分之2-2又5分之2×3又4分之3÷2又2分之1
=12+2/5-(2+2/5)×(3+3/4)÷(2+1/2)
=12+2/5-(12/5)×(15/4)×(2/5)
=12+2/5-18/5
=12-16/5
=44/5;
如果本题有什么不明白可以追问,