1.12.4-（0.4+12.8/0.8)*0.5
=12.4-（0.4+16)*0.5
=12.4-16.4*0.5
=12.4-8.2
=4.2
2.137.4*125-56.4*125-125
=125*(137.4-56.4-1)
=125*80
=10000