Answer:
the temperature at 7 am was -36.7 degrees.
Explanation:
Let's denote the temperature at 7 am by "x". Since the temperature increased by 8.4 C between 7 am and 11 am, we can set up the equation:
x + 8.4 = -28.3
Subtracting 8.4 from both sides, we get:
x = -36.7
Therefore, the temperature at 7 am was -36.7 degrees.