Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 4 - Section 4.4 - Systems of Linear Equations and Problem Solving - Exercise Set - Page 320: 26

Answer

rowing speed: 5.25 mph, current speed: 2.75 mph

Work Step by Step

10 miles = (x+y)*1.25 (downriver) 10 miles = (x-y)*4 (upriver) $10=(x+y)*1.25$ $10=(x-y)*4$ $10=(x+y)*1.25$ $1.25x+1.25y=10$ $10=(x-y)*4$ $4x-4y=10$ $1.25x+1.25y=10$ $4x-4y=10$ $1.25x+1.25y=10$ $4*(1.25x+1.25y=10)$ $5x+5y=40$ $4x-4y=10$ $5/4*(4x-4y=10)$ $5x-5y=12.5$ $5x+5y=40$ $5x-5y=12.5$ $5x-5y+5x+5y=12.5+40$ $10x=52.5$ $10x/10=52.5/10$ $x=5.25$ $10=(x-y)*4$ $10=(5.25-y)*4$ $10/4=(5.25-y)*4/4$ $2.5=5.25-y$ $y+2.5=5.25$ $y=2.75$
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