There are $$15$$ chairs and $$20$$ cups. So the ratio of chairs to cups is $$15:20$$. The simplest form is $$3:4$$. 
In your family, there are $$15$$ chairs, $$5$$ tables, and $$20$$ cups. What is the ratio of chairs to cups? 
Options:
a: $$15:5$$ 
b: $$5:15$$ 
c: $$5:20$$ 
d: $$3:4$$ 