Answer:
3 represents: For every decrease of 1°F, three more cups of hot chocolate will be sold.
Step-by-step explanation:
Consider the provided equation.
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The relationship between the number of cups, n, of hot chocolate sold per day in a coffee shop and the average daily temperature, T, in degrees Fahrenheit.
The provided equation can be written as:

If we observe we can find that the above model is same as the slope intercept form
. Where m is the slope.
Therefore, -3 represents the slope of the function.
The "minus" sign represents the slope of line is downward.
If we Substitute T=0 in provided equation we get N=456
That means when temperature is 0 degrees Fahrenheit the number of cups (N), of hot chocolate sold per day in a coffee shop is 456.
If we Substitute T=1 in provided equation we get N=453
If we Substitute T=-1 in provided equation we get N=459
Therefore, If we increase temperature the number of cups decreases.
Hence, the meaning of 3 in equation is: For every decrease of 1°F, three more cups of hot chocolate will be sold.