括号里最大能填几？
30×　   　＜140               70×　   　＜558           
60×　   　＜342              40×　   　＜236          
80×　   　＜154              70×　   　＜201
50×　   　＜398               90×　   　＜261           
80×　   　＜300              60×　   　＜470          
20×　   　＜175              90×　   　＜612．