Question 1 Next Generation Quantitative Reasoning, Algebra, and Statistics Practice Test for the ACCUPLACER^® test

Sally lives in Antarctica. In the afternoon she measures the temperature to be $-4^\circ C$. Eight hours later she measures the temperature to be $-18^\circ C$. Three hours later she measures again and finds it to be $-23^\circ C$. The following morning she measures one last time and finds the temperature to be $-2^\circ C$.

What is the absolute value of the difference between the lowest and highest measured temperatures?