## Introductory Algebra for College Students (7th Edition)

$x=16$
Let x = the unknown number Then "the quotient of three times a number and four" means $3x\div4$ or $\frac{3x}{4}$ "decreased by three" means $\frac{3x}{4}-3$ Thus, the equation that represents the situation is: $\frac{3x}{4}-3=9$ Use the addition property of equality to add 3 to both sides of the equation. $\frac{3x}{4}-3+3=9+3$ $\frac{3x}{4}=12$ Use the multiplication property of equality to multiply both sides of the equation by 4. $\frac{3x}{4}\times4=12\times4$ $3x=48$ Use the multiplication property of equality to divide both sides of the equation by 3. $3x\div3=48\div3$ $x=16$