Q. If 7@9@10=8, 9@11@30 =5, 11@17@21=13, what is the value of 23@4@15?

Explanation : 

Pattern Analysis

The pattern here is to add all the numbers and then add the digits of the resulting sum.

Let’s look at the examples:

1. 7@9@10 = 8
   Add all numbers: 7 + 9 + 10 = 26
   Add all digits: 2 + 6 = 8
2. 9@11@30 = 5
   Add all numbers: 9 + 11 + 30 = 50
   Add all digits: 5 + 0 = 5
3. 11@17@21 = 13
   Add all numbers: 11 + 17 + 21 = 49
   Add all digits: 4 + 9 = 13

Now, let’s apply this pattern to find the value of 23@4@15:

Add all numbers: 23 + 4 + 15 = 42
Add all digits: 4 + 2 = 6

So, 23@4@15 = 6, which corresponds to option (a).