# Chapter 2 - Section 2.5 - An Introduction to Problem Solving - Exercise Set: 17

$x=5$

#### Work Step by Step

Let x = the unknown number Then "9 times a number" means $9x$ "30 more than 3 times a number" means $30+3x$ Thus, the equation that represents the situation is: $9x=30+3x$ Use the addition property of equality to subtract 3x from both sides of the equation. $9x-3x=30+3x-3x$ $6x=30$ Use the multiplication property of equality to divide both sides of the equation by 6. $6x\div6=30\div6$ $x=5$

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