3
algebra

A chemist needs 10 liters of 20% acid solution. She has 10% solution and 30% solution. How many liters of 10% solution should she use?

A

4

B

5

C

8

D

2

Correct Answer: B

Choice Ahoice D is the correct answer.

  1. Define: 10% = xx, 30% = 10−x10 - x.
  2. Equation: 0.10x+0.30(10−x)=0.20(10)0.10x + 0.30(10 - x) = 0.20(10)
  3. Simplify: 0.1x+3−0.3x=20.1x + 3 - 0.3x = 2
  4. Combine: −0.2x+3=2-0.2x + 3 = 2
  5. Subtract 3: −0.2x=−1-0.2x = -1
  6. Divide by -0.2: x=5x = 5
  7. Verify: 0.5+1.5=20.5 + 1.5 = 2 ✓

Choice Ahoice C is incorrect because calculation error.

Choice Ahoice D is incorrect because calculation error.

Choice Ahoice C is incorrect because calculation error.

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Linear Functions Set 30