Answer
$x=16$
Work Step by Step
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.
$3x\div3=48\div3$
$x=16$
