Solution for #40

Let b be the number of birds, and c be the number of cages. The problem gives us two equations, which we can merge together to solve for c:

           b = c + 1
           c = b/2 + 1
       c - 1 = b/2
      2c - 2 = b
      2c - 2 = c + 1
      2c - c = 1 + 2
           c = 3 

Now we substitute 3 for c in one of the original equations to discover that b equals 4. So there are four canaries and three cages.