Question: Can you give me some step-by-step instructions for this math problem: A farm has 10 2-legged animals and 15 4-legged animals. If all animals are healthy, how many pairs of animal legs in total are on the farm?
Answer: 
2-legged animals have 2 legs. Therefore 10 2-legged animals will have 10*2=20 legs
4-legged animals have 4 legs. Therefore 15 4-legged animals will have 15*4=60 legs
In total there are 20+60= 80 legs
A pair of legs equals 2 legs. If there are 80 legs on the farm, there will be 80/2= 40 pairs of legs