Question

Which is NOT proportionate to 15/45 3/9 3/15 1/3 30/90

Answer 1

You would reduce each of them down by dividing both the top and bottom by the same number, so 15/45 turns into 1/3
3/9 - 1/3
3/15 - 1/5
1/3
30/90 - 1/3
The only one that's different is 3/15