Answer: 7:3
Step-by-step explanation:
15 chairs are red
35 are blue
35:15
Simplifies to
7:3
Here we have a system of equation like this:

from the first equation we get:

Substitute in the second equation we get:

Substitute i the first equation again we get:

We deduce that:

A is bigger than B.
The answer is 12. You find this by counting all of the numbers to the right of the line (referred to as "leaves" in this stem-and-leaf plot)