Answer:
The equation that represents the line of Paul's grade downfall is:
y = (-20)x + 130
This equation states that for every decrease of 1 in the value of x (representing the number of weeks), the value of y (representing Paul's math average) decreases by 20.
Step-by-step explanation:
To find the equation that represents the line of Paul's grade downfall, we can use the two given points to plot the line on a coordinate plane. The point (2, 90) represents the value that after 2 weeks, Paul's math average is 90, and the point (4, 50) represents the value that after 4 weeks, Paul's grade has dropped to 50. We can plot these two points on the coordinate plane as follows:
(2, 90)
(4, 50)
To find the equation of the line that passes through these two points, we can use the slope-intercept form of a linear equation, which is y = mx + b, where m is the slope of the line and b is the y-intercept.
To find the slope of the line, we can use the formula:
m = (y2 - y1) / (x2 - x1)
Substituting the coordinates of the two points, we get:
m = (50 - 90) / (4 - 2)
= -40 / 2
= -20
To find the y-intercept of the line, we can substitute the coordinates of one of the points and the slope into the slope-intercept form of the equation:
y = mx + b
Substituting the coordinates of the point (2, 90) and the slope of -20, we get:
90 = (-20)(2) + b
= -40 + b
= b - 40
Solving for b, we get:
b = 90 + 40
= 130