9.8*62.5*1.25—12.5*0.625*18

98*0.625*12.5-12.5*0.625*18
=12.5*0.625*(98-18)
=12.5*5/8*80
=12.5*50
=625

9.8*62.5*1.25—12.5*0.625*18
=9.8*6.25*12.5—12.5*6.25*1.8
=6.25*12.5(9.8-1.8)
=6.25*12.5*8
=6.25*100
=625

625啊～