Hello there, you can answer it like this:
25:45, you can turn into a fraction
25/45.
Now, you can divide 25 and 45 divided by the greatest number possible.
Answer: 5.
So, the greatest number is five and divide both of them by five.
25 ÷ 5 = 5
45 ÷ 5 = 9 .
Your answer is 5/9.
HOPE THIS HELPS.