3－5／8÷25／28－3／10
=3-7/10-3/10
=3-(7/10+3/10)
=3-1
=2
4／5×［13／16÷（3／4＋1／3）］
=4/5×[13/16÷13/12]
=4/5×[13/16×12/13]
=4/5×3/4
=3/5