2017 AMC 10B Problem 5

Below is the professionally curated solution for Problem 5 of the 2017 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2017 AMC 10B solutions, or check the answer key.

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Concepts:system of equationslinear equation

Difficulty rating: 900

5.

Camilla had twice as many blueberry jelly beans as cherry jelly beans. After eating 10 pieces of each kind, she now has three times as many blueberry jelly beans as cherry jelly beans. How many blueberry jelly beans did she originally have?

1010

2020

3030

4040

5050

Solution:

Let the number of cherry jelly beans be cc and let the number of blueberry jelly beans be bb

Then, we know b=2cb = 2cb10=3(c10)b-10=3(c-10) from the first and second statements respectively.

Therefore, 2c10=3c302c-10 = 3c-30c=20.c=20. This means that b=220=40.b = 2\cdot 20=40.

Thus, the correct answer is D .

Problem 5 in Other Years