Algebra: A Combined Approach (4th Edition)

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

Chapter 4 - Section 4.3 - Solving Systems of Linear Equations by Addition - Exercise Set: 45


The answer is 6.

Work Step by Step

Using n as the number we don't know in the equation, three times a number subtracted from 20 is 2, the equation would be written as 20 - 3n = 2. To solve the equation, add 3n to both sides, then subtract 2 from both sides, lastly divide both sides by 3 to get 6 as the value for n. It is possible to solve this equation by subtracting 20 from both sides as the first step, but then it would require that both sides are divided by a negative number to solve for n. There is nothing wrong with this way, however, dividing by negatives creates more opportunity for silly mistakes. Therefore, it is best to make the variable and its coefficient positive if possible.
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