Hey there!
Let's think about it.
When you have regular plain old whole numbers, and you want to find an equal number, the only thing to do is multiply by one.
It's no different with fractions. When we want to find an equivalent fraction, we multiply by some version of one, like 2/2 or 4/4. We'll use 2/2.
We have:
1/4(2/2) = 2/8
And we know that it;s equal because when we divide the top and bottom by 2, we get 1/4.
Hope this helps!