SOLUTION: Lisa Chen invested $24,000, part of it at 8% and the rest at 7.2%. How much did she invest at each rate if her income from the 8% investment is 2/3 that of the 7% investment? Thi

Question 37342: Lisa Chen invested $24,000, part of it at 8% and the rest at 7.2%. How much did she invest at each rate if her income from the 8% investment is 2/3 that of the 7% investment?
This is a multiple choice question so by inserting different answers I was able to figure out that the answers are $15,000 at 7.2% and $9,000 at 8%. I still don't know how to do the problem though. Please help me with this one. Thanks!!
Answer by checkley71(8403) (Show Source): You can put this solution on YOUR website!
X*.08=2/3*.072(2400-X) OR .08X=.048(2400-X) OR .08X=115.2-.048X OR
.08X+.048X=115.2 OR .128=115.2 OR X=900 THEN Y=2400-900 OR Y=1500
PROOF 900*.08=2/3*.072*1500 OR 72=2/3*108 OR 72=216/3 OR 72=72
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