Basic College Mathematics (9th Edition)

Published by Pearson
ISBN 10: 0321825535
ISBN 13: 978-0-32182-553-7

Chapter 9 - Basic Algebra - 9.8 Using Equations to Solve Application Problems - 9.8 Exercises: 39

Answer

His age is $30$ years old while his sister's age is $21$ years old.

Work Step by Step

1. Finding the person's age Let $x = $ the person's age (person's age) + (sister's age) $= 51$ $(x) + (x - 9) = 51$ $2x - 9 = 51$ $2x = 60$ $x = \frac{60}{2}$ $x = 30$ years old 2. Finding his sister's age Let $S =$ his sister's age $S = x - 9$ $S = 30 - 9$ $S = 21$ years old
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.