——40 & amp； *X+ 140 for sale. All right, let's put this step aside.
The ratio of surplus to sale is 1: 3, 1+3=4, which means that three quarters of the total amount is sold, and the rest is 1.
Simply put, 40% becomes 2/5.
2/5x+ 140=3/4x
3/4x-2/5x= 140
(3/4-2/5)x= 140
7/20x= 140
x= 140*20/7
x=400
A:? .