# The difference of a number p and -9 is 12. What is the number?

Jan 13, 2017

$p = 3$

#### Explanation:

We can write the equation from this word problem by looking at each part of the question.

"The difference of" is saying to subtract what follows.

"a number $p$ and $- 9$ means we have to subtract $\textcolor{red}{- 9}$ from $\textcolor{b l u e}{p}$. Remember, we need to subtract a minus 9 or negative nine - so minus a negative number.

We can write this as $\textcolor{b l u e}{p} - \textcolor{red}{- 9}$

In math the word "is" means equal to or $=$.

And the expression is equal to $12$.

Writing the entire problem out gives:

$\textcolor{b l u e}{p} - \textcolor{red}{- 9} = 12$

We can rewrite as:

$\textcolor{b l u e}{p} + \textcolor{red}{9} = 12$

Solving:

$\textcolor{b l u e}{p} + \textcolor{red}{9} - 9 = 12 - 9$

$\textcolor{b l u e}{p} + 0 = 3$

$p = 3$