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．