Question

the temperature was $-13 mathrm{^circ f}$ and then dropped 5 degrees.
what was the final temperature?

Explanation:

Step1: Define initial temperature

Initial temperature: $T_0 = -13^\circ\text{F}$

Step2: Subtract temperature drop

Final temperature: $T = T_0 - 5$
$T = -13 - 5$
$T = -18$

Answer:

$-18^\circ\text{F}$