Thinking Mathematically (6th Edition)

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

Chapter 8 - Personal Finance - 8.3 Simple Interest - Exercise Set 8.3 - Page 512: 27

Answer

$r=\dfrac{A-P}{Pt}$

Work Step by Step

Distribute $P$ to obtain: $A=P+Prt$ Subtract $P$ on both sides to obtain: $A-P=Prt$ Divide $Pt$ on both sides to obtain: $\dfrac{A-P}{Pt} = \dfrac{Prt}{Pt}$ Cancel the common factors to obtain: $\require{cancel} \dfrac{A-P}{Pt} = \dfrac{\cancel{P}r\cancel{t}}{\cancel{Pt}} \\\dfrac{A-P}{Pt} = r$
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