Instruction:
Let’s solve the following math problem. Each rabbit has 4 feets and each duck has 2 feets. If there are in total 25 heads and 88 feets, how many rabbits and how many ducks are there?

Response:
We can use equations to solve this problem. Let the number of ducks be X and the number of rabbits be Y. We have 
X+Y = 25 (1) 
2X + 4Y = 88 (2). 
From the first equation, we know that X = 25-Y and we can substitute this into the second equation (2), and we get
2(25-Y) + 4Y = 88
Which can be simplified to 50 + 2Y = 88 and we have Y = 19.
We substitute the value into (1), we will then get X = 6. 
There are 6 ducks and 19 rabbits!