2 1/2 - 17/24 = 5/2 - 17/24 = (60 - 17)/24 = 43/24 = 1 19/24
5300*50+4200*90=
5300*50=265000
4200*90=378000
265000+378000=643000
720*700-360*80=
720*700=504000
360*80=28800
504000-28800=475200