A shopkeeper marks up an article by 60% on its cost price. He allows a discount of 25% on the marked price. If the selling price of the article is Rs 900, then find the cost price (in Rs).

The correct answer is 750.

Let's find the cost price step-by-step.

Step 1: Understand the relationship between Cost Price (CP), Marked Price (MP), and Selling Price (SP).
Let the cost price of the article be $CP$.
The shopkeeper marks up the article by 60% above its cost price. Therefore, the marked price ($MP$) is:
$MP=CP+60\%ofCP$
$MP=CP\times \left(1+0.60\right)=1.6\times CP$

Step 2: Apply the discount to find the Selling Price (SP).
A discount of 25% is allowed on the marked price. So, the selling price ($SP$) is:
$SP=MP-25\%ofMP$
$SP=MP\times \left(1-0.25\right)=0.75\times MP$

Step 3: Express SP in terms of CP.
Substitute the expression for $MP$ from Step 1 into the equation for $SP$:
$SP=0.75\times \left(1.6\times CP\right)$
$SP=1.2\times CP$

Step 4: Calculate the Cost Price (CP).
We are given that the selling price of the article is Rs 900.
$900=1.2\times CP$
$CP=\frac{900}{1.2}$
$CP=750$

Thus, the cost price of the article is Rs 750.