Here is your equation:

Let's start with the equation in | |. ←These signs are used for absolute value. Absolute value is the distance between a number and 0. Absolute value is ALWAYS positive.
Here is the equation in the | |:

The negative number is greater than the positive number. That means your answer will be negative. When adding a greater negative number and a positive number, you can just subtract the positive number from the negative number and add the negative(-) sign.

Add the (-) sign and it becomes:

Remember you have to find the absolute value of it, and absolute value is ALWAYS positive.

Here is your new equation:

In the parentheses, the positive number is greater than the negative number. An easier way to do it is to subtract the negative number from the positive number.

Here is your new(and last) equation:

Add:

The answer choice that matches is C, so that means your answer is C. 39
If you have any questions, feel free to ask in the comments! :)