Mrs. Mary. invested $36,000; part at 5%, and part at 8%. The total interest on the investment was $2,520. How much did she invest at each rate?
Choose one.
A) x=$15,000, y =$30,000 B) x=$16,000, y =$32,000 C) x=$12,000, y =$24,000 D) x=$5,000, y =$10,000 E) x=$13,000, y =$26,000
I approached this question like a mixture problem.   I don't like the wordingpartat 5% andpartat 8% because we have variables x and y in the answer choices and I have no idea which one is x or y.   Anyway here's how I did it.   0.05(x) + 0.08(y) = 0.07(x+y)   0.01(y) = 0.02(x)   y = 2x   Note: 0.07(x+y) because $2,520 is 7% of 36,000   In which answer choice is y = 2(x)   Answer x=$12,000, y =$24,000
<result>C</result>
Mrs. Mary. invested $36,000; part at 5%, and part at 8%. The total interest on the investment was $2,520. How much did she invest at each rate?