$12$ is the product of $6$ and $2$.Then multiple $3$ by $6$ is the number of red cards. The total number of cards is $30$. 
You have $12$ green cards and the ratio of your red cards to green cards is $3:2$. How many cards do you have? 
Options:
1. $18$ 
2. $20$ 
3. $$24$$ 
4. $30$ 