Let’s do A first.
We have 1/4, ?/8, and ?/12. What times 4 gives you 8? Or what is 8 divided by 4? 2. So we will multiply the numerator by 2 as well. 2/8. Now what’s 12 divided by 4? 3. So multiply the numerator by 3. 3/12. So you should have:
1/4 = 2/8 = 3/12
Now B is 1/2, ?/8, ?/10. So the same process again. 8 divided by 2 is what? 4. Multiply the numerator by 4 as well. 4/8. 10 divided by 2 is what? 5. Multiply the numerator by 5. 5/10. So you should have:
1/2 = 4/8 = 5/10.
Now C. 3/4, ?/8, ?/12. Again. 8 divided by 4 is 2. Multiply the numerator by 2. 6/8. 12 divided by 4 is 3. Multiply the numerator by 3. 9/12. So:
3/4 = 6/8 = 9/12
Now D. 2, ?/2, ?/4. 2 can be rewritten as 2/1. So 2 divided by 1 is 2. Multiply the numerator by 2. 4/2. 4 divided by 1 is 4. Multiply the numerator by 4. 8/4. So:
2 = 4/2 = 8/4
Hope this helped