so the total number is 60, and we can just divide it by (3+9) and then distribute accordingly.
[tex]\stackrel{ratio~3:9}{60}\qquad \qquad 3\cdot \frac{60}{3+9}~~ :~~9\cdot \frac{60}{3+9}\implies 3\cdot \frac{60}{12}~~ :~~9\cdot \frac{60}{12} \\\\\\ 3(5)~~ : ~~9(5)\implies 15~~:~~45[/tex]
