Answer: 13
Step-by-step explanation: Before taking the absolute value of a number, always simplify what's inside the absolute value as much as possible.
So here we have -5 - 8 inside the absolute value which can be thought of as -5 + -8 or -13. So we have |-13| which is +13.
Remember, absolute value means distance from zero on a number line so the absolute value of any number will be the positive version of that number.