How do you work ratio tables in 7th grade

Ratio tables are like proportional relationships (if you know what that is), and you have to do this:
6:9 is related to a:45 we don't know a, but since the prior ratio is related to this one, you simply take 9 times what is 45. The answer is 5, so then you multiply 6 times 5 to get 30. Then keep building off of that. The next problem will be 48, then 72.
The bottom ratios start with 10:15. 15 times 3 is 45 so 10 times 3 is 30. The next one is 100, then 70. Hope this helps, sorry that it's confusing!