Question

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

Answer 1

40. This is because:
1+4= 5.
2+5= 7. Now you must take the 5 from the previous answer and add it to your new answer, which then gives you 12.
Now 3+6=9. Take 12 and add it to 9, which will give you 21. Follow the pattern to get the next answer, which is 40.