Okay, so the possible numbers he can choose are :
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Pick out all the odd numbers and multiples of 5.
1, 3, 5, 7, 9, 10
Count how many numbers are odd and are a multiple of 5.
6 numbers are odd or are a multiple of 5.
So, out of 10 numbers, 6 are odd or are a multiple of 5,
Therefore, our answer is 6/10
If you would like it simplified, it would be 3/5
Or, as a decimal, it would be 60%
~Hope I helped!~