2003 AMC 8 Problem 4

Below is the professionally curated solution for Problem 4 of the 2003 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2003 AMC 8 solutions, or check the answer key.

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Concepts:system of equations

Difficulty rating: 720

4.

A group of children riding on bicycles and tricycles rode past Billy Bob's house. Billy Bob counted 77 children and 1919 wheels. How many tricycles were there?

22

44

55

66

77

Solution:

Let bb be the number of bicycles and tt be the number of tricycles. Then we can set up the following system of equations: b+t=7,2b+3t=19. \begin{gather*} b + t = 7, \\ 2b + 3t = 19. \end{gather*} Multiplying the first equation by 22 and subtracting from the second equation, we get t=5.t = 5.

Thus, C is the correct answer.

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