# How do you evaluate 3x + 15 when x= 12?

Substitute the given value for x into the equation and then solve.

#### Explanation:

In this case the given x-value is 12, so we put 12 in place of the x giving us the expression $3 \left(12\right) + 15$. Then we solve according to PEMDAS.
Parentheses: in this case, there is nothing to solve inside of the parentheses
Exponents: none
Multiplication: here we multiply $3 \cdot 12 = 36$
Addition: now we add $36 + 15 = 51$
Subtraction: none

So the final answer is 51.

Mar 4, 2018

$3 \left(12\right) + 15 = 51$

#### Explanation:

Replace the $x$ with the $12$. Multiply the $3$ by the $12$ and then add $15$ to that answer.

Mar 4, 2018

$3 \left(12\right) + 15 = \textcolor{b l u e}{51}$

#### Explanation:

Substitute $12$ for $x$ in the equation.

$3 \left(12\right) + 15 =$

$36 + 15 =$

$51$