Bridget's gas usage forms a linear function defined by y = (-8/5)x + 13. This means each lawn mowed reduces gas by 8/5 gallons, starting with 13 gallons initially.
Gathering Information:
Bridget has 13 gallons initially (y-intercept).
Each lawn mowed reduces the remaining gasoline by a constant amount (slope).
We need to find the equation of the line representing this relationship (y = mx + b).
Determining the Slope (m):
a) Choose two convenient points from the graph:
Point 1: (0, 13) (initial point)
Point 2: (5, 5) (after 5 lawns mowed)
b) Calculate the slope (m) using the formula:
m = (y2 - y1) / (x2 - x1)
m = (5 - 13) / (5 - 0)
m = -8 / 5
Finding the y-intercept (b):
We already know the y-intercept is 13 because it's the initial amount of gasoline (when x = 0).
Constructing the Equation:
Now that we have the slope (m = -8/5) and the y-intercept (b = 13), the equation becomes:
y = (-8/5)x + 13
Verification:
This equation accurately reflects the linear relationship between x (lawns mowed) and y (remaining gasoline):
When x = 0 (no lawns mowed), y = 13 (13 gallons left).
When x = 5 (5 lawns mowed), y = 5 (5 gallons left).
Therefore, the equation y = (-8/5)x + 13 is the solution that represents Bridget's gas usage.