Dog is 10 more than cat and together equal 24.
What two numbers are 10 apart and add up to 24? 17 plus 7.
So, dog is 17 and cat is 7.
Dog plus rabbit is 20. 20 less 17 is 3.
So rabbit is 3.
17 plus 7 plus 3 is 27.
That took me about a minute to do in my head, and I have no idea how to do algebra.
Yes, it was a simple as that with no equation.