Question

1+4=5; 2+5=12; 3+6=21; 8+11=?

Answer 1

The pattern:
So it goes, 1, 2, 3, as the first number in each equation right.
Then it goes 4,5,6 as the second number in each equation.
In other words, the first number + 3 = the second number

The sum or 3rd number is a zig zag pattern from the first and second numbers as shown below.
1 2 3 4 5 6   7  8   9 
4 5 6 7 8 9 10 11 12

1 * 5 = 5, 2 * 6 = 12, 3 * 7 = 21 .... 8 * 12 = 96

So the answer of 8+11=96

Answer 2

8 + 11 = 40. Because, 8+11= 19 and 19 + 21 is 40.