Answer:
N=1
Explanation:
If N=1 then...
5 times 1 is 5
5 is a multiple of 10
BUT it says the ONE possible solution.
So that means if I try anything else it should fail right?
let's try N=2
5 times 2 is 10
10=10 it can't be a multiple if it equals itself.
N=3
15 isn't a multiple of 10
Anything after that is too high so we found it!!
Glad I can help!!