To find the amount of change in temperature every hour, we can set up the following equation:
\[ x \times 5 = -12 \]
Here, \( x \) represents the change in temperature each hour, and since the temperature is dropping, we use -12 to indicate a decrease.
Now, we can solve for \( x \):
\[ x = \frac{-12}{5} \]
Calculating this gives:
\[ x = -2.4 \]
So, the temperature dropped by 2.4° every hour.