There are two ways to solve the above problem.

The first way to find the solution is to add the equation, then combine the sum with that of the previous equation.

The second solution involves multiplying the second number of the equation by the number you are adding to it. The correct answer could either be 40 or 96.

In the first case

For the second case

We have getting two solutions here this solution are getting viral in internet but we can logically establish that 96 is true

In first solution

Summing two terms , then combine the sum with that of the previous equation. Also the number are in a pattern

Ie first 3 terms of the questions

So we can assume that 8+11 is not the 4th term and it is 8th term of the pattern so we can't add 21 to 8th term.

If the pattern continued we have getting same 96 in the second solution so 96 is logically correct answer