I have two columns, one (Column A) that repeats and the other (column B) that
has a none repeating number. I need to have a formula that will give me
result in column C that will display all the results from column B when
searching for a number is column A. Like when looking for the number 10 in
Column A, Column B has two numbers (1 & 7) that match that will be displayed
in Colomn C.
Does anyone have an idea on how to do this, I used Vlookup but it will only
give me the first answer. Any help would be appreciated, thanks in advance.
Here is an example:

Column A Column B Column C
10 1 1,7
11 2 2,8
12 3 3,9
13 4 4
14 5 5,11
15 12
10 7 1,7
11 8 2,8
12 9 3,9
13 4
14 11 5,11
15 12 12