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
