The table given below shows the average number of articles (A, B and C) sold by Pesto company in three different months. It also shows the percentage of article A sold by Pesto company out of the total number of articles sold in these months. Table also reflects the total number of article C sold in these months. Read the table carefully and answer the following questions.

Months	Average number of articles sold	Percentage of article A sold	Total number of articles C sold
April	100	40%	100
May	120	30%	70
June	72	25%	80

If the price of each article at which articles A, B and C sold in the month of April are Rs. 10, Rs y and Rs. (y + 20) respectively, then the total revenue generated by selling these articles in the month of April is Rs. 4100. Find the value of 3y.

The correct answer is 15.

To find the value of $3y$, let's break down the information given for the month of April step-by-step:

Step 1: Find the total number of articles sold in April.
The table shows that the average number of articles (A, B, and C) sold in April is 100.
Since there are three types of articles (A, B, and C), the total number of articles sold is:

$\text{Total Articles}=3\times 100=300$

Step 2: Find the number of individual articles (A, B, and C) sold in April.
- Article A: The percentage of article A sold is 40% of the total articles sold in April:

$\text{Number of Article A}=40\%\text{of}300=\frac{40}{100}\times 300=120$

- Article C: The total number of article C sold is directly given in the table as:

$\text{Number of Article C}=100$

- Article B: The number of article B sold is the remaining portion of the total articles:

$\text{Number of Article B}=\text{Total Articles}-(\text{Article A}+\text{Article C})$

$\text{Number of Article B}=300-(120+100)=300-220=80$

Step 3: Set up the revenue equation.
The selling prices of each article in April are:
- Price of A = Rs. 10
- Price of B = Rs. y
- Price of C = Rs. (y + 20)
The total revenue generated is Rs. 4100. Therefore:

$(\text{Number of A}\times \text{Price of A})+(\text{Number of B}\times \text{Price of B})+(\text{Number of C}\times \text{Price of C})=4100$

Substitute the values into the equation:

$(120\times 10)+(80\times y)+(100\times (y+20\left)\right)=4100$

$1200+80y+100y+2000=4100$

Combine the like terms:

$3200+180y=4100$

Subtract 3200 from both sides:

$180y=4100-3200$

$180y=900$

Solve for y:

$y=\frac{900}{180}=5$

Step 4: Find the value of 3y.
Substitute the value of y into the required expression:

$3y=3\times 5=15$