Answer:
The equation is:
y = -15*x + 1200
and:
a = 120
b = 70
c = -1500
Step-by-step explanation:
This seems to be a linear relationship.
A linear relationship can be written as:
y = a*x + b
where a is the slope and b is the y-axis intercept.
For a line that passes through the points (x1, y1) and (x2, y2), the slope can be written as:
a = (y2 - y1)/(x2 - x1).
Here we know that our line passes through the points (60, 300) and (20, 900)
Then the slope of this line is:
a = (900 - 300)/(20 - 60) = 600/(-40) = -15
Then this line is something like:
y = -15*x + b
To find the value of b, we know that this line passes through the point (60, 300) then when x = 60, we have y = 300.
Replacing these values in the above equation we get:
300 = -15*60 + b
300 + 15*60 = b = 1200
Then:
y = -15*x + 1200.
Now that we have this equation, we can complete the table.
a is the value for y, when x = 72
Then we can replace x by 72 in the above equation:
a = -15*72 + 1200 = 120
a = 120
b is the value of x when y = 150, then we need to replace y by 150
150 = -15*b + 1200
150 - 1200 = -15*b
(150 - 1200)/-15 = b = 70
then:
b = 70
c is the value of y when x = 180, then we need to replace x by 180.
c = -15*180 + 1200
c = -1500
