Question

What is the sum of 11 and difference of 9?

Answer 1

Sum of 11 ⇒ (you must list all that add up to 11) 
1+10=11
2+9=11
3+8=11
4+7=11
5+6=11 

The answer is    1+10=11
 cause the difference between 10 and 1, is 9  

Answer 2

10+1 is the answer .