Question

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

Answer 1

`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 `color(red)(-9)` from `color(blue)(p)`. Remember, we need to subtract a minus 9 or negative nine - so minus a negative number.

We can write this as `color(blue)(p) - color(red)(-9)`

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

And the expression is equal to `12`.

Writing the entire problem out gives:

`color(blue)(p) - color(red)(-9) = 12`

We can rewrite as:

`color(blue)(p) + color(red)(9) = 12`

Solving:

`color(blue)(p) + color(red)(9) - 9 = 12 - 9`

`color(blue)(p) + 0 = 3`

`p = 3`