5/13×4/7×14
=5/13×(4/7×14)
=5/13×8
=40/13
(2/3+8/9)×27
=2/3×27+8/9×27
=18+24
=42
2/9-7/13×2/9
=(1-7/13)×2/9
=6/13×2/9
=4/39
=2/5×1
=2/5
5/7×16÷5/21
=5/7×16×21/5
=16×3
=48
最后一题算式不对
5/13×4/7×14
=5/13×(4/7×14)
=5/13×8
=40/13
(2/3+8/9)×27
=2/3×27+8/9×27
=18+24
=42
2/9-7/13×2/9
=(1-7/13)×2/9
=6/13×2/9
=4/39
=2/5×1
=2/5
5/7×16÷5/21
=5/7×16×21/5
=16×3
=48
最后一题算式不对