Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 6 - Algebra: Equations and Inequalities - 6.3 Applications of Linear Equations - Exercise Set 6.3 - Page 376: 70

Answer

age of Charles Coburn(Uncle)is \[60\] and age of woman is \[20\].

Work Step by Step

Let \[x\] be the current age of Charles Coburn(Uncle). Let \[y\] be the current age of woman. \[x=3y\] …… (1) When Uncle replies “Ah, but in 20 years’ time I shall only be twice be her age. It means: \[x+20=2\left( y+20 \right)\] ...... (2) Now In equation (2)put value of \[x\] from equation(1): \[\begin{align} & 3y+20=2\left( y+20 \right) \\ & 3y+20=2y+40 \\ & y=20 \end{align}\] Put \[y=20\]in equation (1); \[\begin{align} & x=3\left( 20 \right) \\ & x=60 \\ \end{align}\] So, age of Charles Coburn(Uncle)is \[60\] and age of woman is \[20\]. Hence, age of Charles Coburn(Uncle)is \[60\] and age of woman is \[20\].
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