Answer:
4. 0 + 1 = 1
Step-by-step explanation:
since 2/9 is a bit small
and
since 10/11 is almost whole
3 sets or it you could divide which would still give you 3
The number is 3. The math is 5 x 3 = 15 15 - 3 = 12
I think you mean,

You can use the usual formula,

That in this case is,

Where I have used,