OK so if you're wanting 15 and 36 you will need to know what goes into each of them but if you just need 15 then let's try to find that one so, what does go into 15 well let's find out.
15:1×15,3×5
36:1×36,2×18,3×12,4×9,6²
so, based on what we have here there are a lot of answers between numbers 15&36 but one maybe two or more answers for what can go into 15 and 36.
3×12=36
12+3=15
so, the two numbers you need are 3 and 12.
