let the cost price for the articles be is equal to =Rs x; Since cost price of twenty articles is equal to selling price of X articles therefore the equation will be 20*x = X*x + 1/4(X*x) eqn (1) from eqn (1) we can find out the value of X which will be 16 in this case therefore X=16 b) is the correct option X is the number of articles whose selling price will be equal to the cost price of twenty articles after getting the profit of twenty five percent.