2005 AMC 12A Problem 1

Attempt Problem 1 of the 2005 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2005 AMC 12A solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

1.

Two is 10%10\% of xx and 20%20\% of y.y. What is x−y?x - y?
11
22
55
1010
2020
Answer: D
Concepts:percentagelinear equation
Small hint:
10%10\% of xx means 0.1x0.1x
Big hint:
Solve 0.1x=20.1x = 2 and 0.2y=20.2y = 2 separately
Solution:
From 0.1x=20.1x = 2 we get x=20,x = 20, and from 0.2y=20.2y = 2 we get y=10.y = 10.
Therefore x−y=20−10=10.x - y = 20 - 10 = 10.
Thus, the correct answer is D.
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