The values of Stock A and Stock B on a particular day are Rs. 50 and Rs. 80, respectively. An investor invests Rs. 100 in Stock A and Rs. 80 in Stock B. He sells all the stocks the next day when the value of Stock A is Rs. 55 and Stock B is Rs. 70. The profit made by the investor is Rs. ________

To determine the profit made by the investor, calculate the total cost price and total selling price:

1. Number of stocks purchased:

   • Number of units of Stock A = $\frac{100}{50} = 2$

   • Number of units of Stock B = $\frac{80}{80} = 1$

2. Total Investment (Cost Price):

   $$\text{Total CP} = 100 + 80 = \text{Rs. } 180$$

3. Total Selling Price on the next day:

   • Selling price of Stock A = $2 \times 55 = \text{Rs. } 110$

   • Selling price of Stock B = $1 \times 70 = \text{Rs. } 70$

   $$\text{Total SP} = 110 + 70 = \text{Rs. } 180$$

4. Profit:

   $$\text{Profit} = \text{Total SP} - \text{Total CP} = 180 - 180 = \text{Rs. } 0$$

Thus, the correct option is A.