Which ratios form a proportion a. 4/10 and 10/25 b. 3/5 and 9/25 c. 4/9 and 9/4 d. 4/11 and 6/13

Now, in order for it to be a proportion, both the number and the denominator must turn to the other number by the same method. I'll clarify when we do the steps.

So, the first one is 4/10 and 10/25

The first thing that you would do is divide 10 by 4, and then 25/10

When you do that, it turns out that they both equal 2.5. This means that both the number and denominator go to the new number with the same method, multiplying by 2.5

So, the answer would be A