a.1000-800:4+(100-80:10):2-550=
=1000-200+(100-8):2-550
=1000-200+92:2-550
=1000-200+46-550
=296
b.19+2×14+3×[2+3x(45-95:5)]=
=19+28+3×[2+3×(45-19)]
=47+3×(2+3×26)
=47+3×(2+78)
=47+3×80
=47+240
=287
c.[7×3-5)+2×6:4+5]×10-[(4+9)×5-60]=
=[(21-5)+12:4+5]×10-(13×5-60)
=(16+3+5)×10-(65-60)
=24×10-5
=240-5
=235
