The equation that represents the relationship between x and y is 

Step-by-step explanation:
Given that a construction crew is extending the length of the center line on a highway.
The length of the line starts out as 6 meters long, which is represented on a coordinate plane as the point (0,6). The crew works for 20 minutes and the line is now 17 meters long, which is represented as the point (20,17).
Let x represents the number of minutes spent working.
Let y represents the length of the line in meters.
We need to determine the equation that represents the relationship between x and y.
The equation can be determined using the formula,

First, we shall determine the slope using the formula,

Substituting the coordinates 
 and
 and 
 , we get,
, we get,


Now, we shall substitute the slope 
 and the coordinate
 and the coordinate 
 in the formula
 in the formula 
 , we have,
, we have,

Simplifying, we get,

 

Thus, the equation that represents the relationship between x and y is 
