0.072×87.5＋8.75×0.28
=0.72×0.1×87.5+8.75×0.28
=（0.72+0.28）×8.75
=1×8.75
=8.75
7.5÷2.5÷0.4
=7.5÷（2.5×0.4）
=7.5÷1
=7.5
7/8÷9×3/5÷35/72
=7/8×72/35×1/9×3/5
=3/251/2÷2/3＝ 5/16×8/15＝8/5×10/16＝