Answer:
x=2/3 double zero
Step-by-step explanation:
There are NO SOLUTIONS.
Substitute the first equation for y in the second equation. You can see it does not work. 6 does not equal 8. Therefore there are no solutions.
I don't know what posts are but i'm assuming you would subtract 21 from 17 and get 4.
Please elaborate on this so that I can help you.