Solution for #34

Let S be the number of sheep and C be the number of chickens. So:

           2S = C
      5S + 3C = 99 

We can rephrase the first equation thusly:

      6S - 3C = 0 

And then we can add this to the second equation, which yields:

          11S = 99 

By solving for S, we find that S equals 9. By substituting back in one of the original equations, we find that C equals 18. So there are nine sheep and eighteen chickens.