Answer: -3 degrees Fahrenheit.
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Explanation:
x = number of hours since 2 AM
y = temperature in degrees Fahrenheit
The starting temperature is -15 degrees, so the y intercept is b = -15.
The temperature goes up 3 degrees each hour, so the slope is m = 3
The equation is y = 3x-15
Now plug in x = 4 since 6 AM is four hours after 2 AM.
We get the following
y = 3x-15
y = 3*4-15
y = 12-15
y = -3
The temperature at 6 AM is -3 degrees Fahrenheit.
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Check:
Start at -15 and add 3 for each hour
It might help to make a number line.
2 AM = -15 degrees
3 AM = -12 degrees
4 AM = -9 degrees
5 AM = -6 degrees
6 AM = -3 degrees
This confirms the answer.
