Question

A picture is enlarged by keeping its width the same and increasing its length. The scatter plot shows the perimeter of the picture (y) for different lengths (x):

Answer 1

Answer: This is the CORRECT answer ----> y = 2x + 20

Step-by-step explanation: slope, y2 - y1/x2 - x1

replace it with these numbers 120 - 60/50 - 20=60/30

than,simplified it we get 2/1. so, now we  have the slope of our equation

y = 2x + b. but we still have b (or where the y intersects.) now are slope we have to change it to 1/2 because we are going backwards. So multiply 60 by .5, Thus will give us 30

Now we have y = 2x + 30, But that's not one of your answer,

So y = 2x + 20 cant be -20 because this is a positive y intersect and We know it is a slope of 2.

Therefore the answer is : y = 2x + 20

ALSO I know it's correct because I got it right on the test!! Hoped I helped :))

Answer 2

Since you have not included the plot, I'll just tell you how to find the function of the graph that you are looking for.
Function of the straight line has the general formula: y = mx + c
where: 
m is the slope of the line and c is the y-intercept

So first we will need to find the slope (m):
Taking two points from the graph (x1,y1) and (x2,y2), the slope can be calculated as follows:
m = (y2-y2) / (x2-x2)

Then, we will need to find the y intercept.
we have the equation y = mx + c and we have m calculated
Take any point that belongs to the line and substitute with the values of x,y and m and then calculate c.

Now you have both m and c calculated, just substitute with the values in the formula.