Introductory Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-805-X
ISBN 13: 978-0-13417-805-9

Chapter 2 - Section 2.5 - An Introduction to Problem Solving - Exercise Set - Page 165: 14


The number is $4$.

Work Step by Step

Let $x$ = the unknown number Then "a number increased by 12" means $x+12$ "four times a number" means $4x$ Thus, the equation that represents the situation is: $x+12=4x$ Subtract $x$ on both sides of the equation to obtain: $12=4x-x \\12=3x$ Divide $3$ on both sides of the equation to obtain: $\dfrac{12}{3} = x \\4 = x$
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