六分之五-四分之三+三分之二（简便运算）八分之三+二分之一-四分之一（同上）

5/6-3/4+2/3
=(5/6-3/4+2/3)*12÷12
=(10-9+8)÷12
=9/12
=3/4
3/8+1/2-1/4
=(3/8+1/2-1/4)*8÷8
=(3+4-2)÷8
=5/8