It's would be 15 grams. Your ratio is x/50=30/100. You then would cross multiply 30×50 and end up with 1500. After that you would divide by 100 and have your answer, 15g.
For an approximation we don't use exact numbers. Seeing as Pennsylvania has a population of around 12.6 million and Ohio has a population near 11.5 million, there is about a difference of 1 million when comparing the populations.
