The total cost of electricity when the business operates for 4 hours is correct.
Slope of a line
The slope of a line is also known as rate of change, The formula for calculating the slope of a line is expressed as:
Slope = y2-y1/x2-x1
If the proportional relationship between the number of hours a business operates and its total cost of electricity is shown in the following graph.
Using the coordinate points (1, 20) and (2, 40)
Determine the slope
Slope = 40-20/2-1
Slope = 20/1
Slope = 20
This shows that the total cost of electricity is $20 when operating business for 1 hour.
According to the coordinate point A (4, 120), this shows that the y-coordinate of point A is represents the total cost of electricity when the business operates for 4 hours.
Learn more on rate of change here: https://brainly.com/question/8728504
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