能简便要简便:5⼀8÷20⼀21÷7⼀12=? 3⼀4×(17⼀18-5⼀9)=? 3⼀7×1⼀15+4⼀7÷15=?

2024-11-16 07:35:09
推荐回答(1个)
回答(1):

5/8÷20/21÷7/12
=5/8* 21/20 * 12/7
=9/8

3/4×(17/18-5/9)
=3/4×(17/18-10/18)
=3/4 ×7/18
=21/72

3/7×1/15+4/7÷15
=3/7×1/15+4/7×1/15
=1/15 ×(3/7 +4/7)
=1/15 × 1
=1/15