While watching a circus show, I counted out the number of acrobats and elephants. I counted 40 legs and 15 heads. How many acrobats did I see in the show?
I want to find the number of acrobats, so I need to use the information about the legs and heads of the acrobats and elephants. I can assume that each acrobat has two legs and one head, and each elephant has four legs and one head. Let me call the number of acrobats x and the number of elephants y. Then I can write two equations based on the given data. The first equation is about the legs: 2x + 4y = 40. The second equation is about the heads: x + y = 15. I can solve this system of equations by substitution. If I solve for x in the second equation, I get x = 15 - y. Then I can plug this into the first equation and get: 2(15 - y) + 4y = 40. Expanding and simplifying, I get: 30 - 2y + 4y = 40, or 2y = 10. So y = 5, which means there are 5 elephants. To find x, I can use the second equation again and get: x = 15 - 5, or x = 10. So there are 10 acrobats. 