5/18*3/7*3/5 3/4*2/3+1/6 8/9*3/4+5/6 7/8-4/7*7/16 2.3/7与5/21

5/18*3/7*3/5
=(5×3×3)/(18×7×5)
=1/14
3/4*2/3+1/6
=1/2+1/6
=3/6+1/6
=4/6
=2/3
8/9*3/4+5/6
=2/3+5/6
=4/6+5/6
=9/6
=3/2
7/8-4/7*7/16
=7/8-1/4
=7/8-2/8
=5/8
3/7与5/21的和的14倍是多少
（3/7+5/21）×14
=3/7×14+5/21×14
=6+10/3
=28/3
3/7与21/5的14倍的
（3/7+5/21）×14
=3/7×14+5/21×14
=6+10/3
=28/3