— It shouldn't take long to clear up after the party if we all volunteer to help. 

— That's right. ______. [ ]

A. Many hands make light work

B. Something is better than nothing

C. The more, the merrier

D. The sooner begun, the sooner done

某校九年级学生毕业时，每个同学都将自己的相片向全班其他同学各送一张作纪念，全班共送了2070张相片．若全班有x名学生，根据题意，列出方程为                .