(8/7-16/13）÷16/13
=(8/7-16/13）×13/16
=13/7-1
=6/7
（2/1×5/4-5/2）÷5/8
=(5/2-5/2) ÷5/8
=0
13/4÷6＋5/6×13/4
=13/4×1/6+5/6×13/4
=13/4(1/6+5/6)
=13/4