能简便的用简便方法。(2/3一2/5)×(3/4÷4/5)=(2/3-2/5)*(3/4*5/4)=(2/3-2/5)*15/16=2/3*15/16-2/5*15/16=5/8-3/8=2/8=1/4
(2/3一2/5)×(3/4÷4/5)= (2/3一2/5)×3/4×5/4=2/3×3/4×5/4-2/5×3/4×5/4=1/2×5/4-2/5×5/4×3/4=5/8-1/2×3/4=5/8-3/8=1/4
这题没法简算