The selling price of a product is fixed to ensure 40% profit. If the product had cost 40% less and had been sold for 5 rupees less, then the resulting profit would have been 50%. The original selling price, in rupees, of the product is

The correct option is 14.

Let the original cost price of the product be CP rupees.
According to the problem, the original selling price (SP) is fixed to ensure a 40% profit. Therefore, we can express the original selling price as:

$$SP=CP+0.40CP=1.40CP$$

Now, let us consider the hypothetical scenario:
1. The new cost price (CP') is 40% less than the original cost price:

$$C{P}^{\prime }$$

2. The new selling price (SP') is 5 rupees less than the original selling price:

$$S{P}^{\prime }$$

3. The profit in this scenario is 50% of the new cost price. This gives us the relation:

$$S{P}^{\prime }$$

Substituting the expressions for SP' and CP' in terms of CP:

$$1.40CP-5=1.50\cdot (0.60CP)$$

Simplifying the right-hand side of the equation:

$$1.40CP-5=0.90CP$$

Rearranging the terms to solve for CP:

$$1.40CP-0.90CP=5$$

$$0.50CP=5$$

$$CP=\frac{5}{0.50}=10$$

So, the original cost price of the product is 10 rupees.
Finally, we calculate the original selling price (SP):

$$SP=1.40\cdot 10=14$$

Thus, the original selling price of the product is 14 rupees.