Question 12 • GA-Algebra: Concepts and Connections A
Fifteen percent of the pigment in paint color A is black. Sixty percent of the pigment in paint color B is black. An unknown amount of paint color B is mixed with 40 ml of paint color A, resulting in a paint that contains 25% black pigment.Which equation can be used to solve for x, the total amount of paint in the mixture of the two colors?
Answer
A
0.15(40) + 0.6x = 0.25(40 + x)
B
0.15(40) + 0.6(x – 40) = 0.25(x)
C
0.15(40) + 0.6x = 0.25(40 – x)
D
0.15(40) + 0.6(x + 40) = 0.25(x)
Explanation
Let x be the total amount of paint in the mixture. Since 40 ml is paint A, the amount of paint B is x − 40 ml. The amount of black pigment is 0.15(40) from paint A plus 0.6(x − 40) from paint B, and this equals 25% of the total mixture, 0.25x. So the equation is 0.15(40) + 0.6(x − 40) = 0.25x, choice B.
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