体积是____ ${\text{cm}}^3$

 华润万家超市某服装专柜在销售中发现：进货价为每件50元，销售价为每件90元的某品牌童装平均每天可售出20件．为了迎接“六一”，商场决定采取适当的降价措施，扩大销售量，增加盈利．经调查发现：如果每件童装降价1元，那么平均每天就可多售出2件，要想平均每天销售这种童装盈利1200元，同时又要使顾客得到较多的实惠，设降价x元，根据题意列方程得（ ）

   Flags have existed for over 3,000 years. The earliest flags were wooden or metal poles with a carving. About 2,000 years ago pieces of fabric were added to some poles for decoration. Over the next 500 years the free-flying part of the flag became more important.