六年级上册人教版数学第二单元分数简便算法练习题 见下
问题描述：
六年级上册人教版数学第二单元分数简便算法练习题 见下
9/4x2/21-5/4x6/5 16/15x21/20x5/1 (6/5-12/5)x36 2/1x3/2x4/3x5/4x6/5
= = = =
(6/5+12/5)x48 12x4/3x12/5 16x(4/3-8/3) 11/8x6/7x4/11
= = = =
急
答
请把分子和分母约掉,再计算