怎样算简便就怎样算
（4800÷12+1）×12           2.4+2.4×3.75+2.4×0.25           ×1.8+×4.2         
（+×）÷           24×+62×                 （0.4+0.5）÷（1.75﹣0.75）×0.5             209+491+258+42                 101×0.33               99×23．