Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 1 - 1.3 - Modeling with Linear Equations - 1.3 Exercises - Page 98: 53


$4000$ dollars at $4.5\%$ and $8000$ dollars at $5\%$.

Work Step by Step

Let $x$ be the amount invested at $4.5\%$ interest. Then the amount invested at $5\%$ interest is $12000-x$. Then our equation is: $0.045x+(12000-x)\cdot0.05=580\\0.045x+600-0.05x=580\\-0.005x=-20\\x=4000.$ Thus I invested $4000$ dollars at $4.5\%$ and $8000$ dollars at $5\%$.
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