Answer with Explanation:

Let C.P. of each article be Re. 1 C.P. of x articles = Rs. x.

S.P. of x articles = Rs. 20.

Profit = Rs. (20 - x).

Therefore, 20 - x /x * 100 = 25

=> 2000 - 100x = 25x

125x = 2000

=> x = 16.