Question

Which number is a factor of 20, but not a multiple of 2? 12, 5, 10 or 4?

Answer 1

factors of 20 are: 1,20:2,10:4,5.
So 1 or 20 is that number

Answer 2

5 is your answer

20/4 = 5 however,

2 x 2.5 = 5 (it doesn't work, cannot have decimals)

so 5 is your answer

hope this helps