In order to determine if the point (20,13) is on the line, it is necessary to write the equation of the line.
The general form of a linear equation is:
y = mx + b
where b is the y-intercept and m is the slope. Y-intercept is the value of y when x = 0. You can observe in the graph that b = 3.
The slope m is conputed by using the following formula:
where (x1,y1) and (x2,y2) are two points of the line. Use the points (0,3) and (6,6), you can select any other two points. Replace these values into the formula for m:
Then, the equation of the line is:
Now, replace the value of x = 20 in the previous equation, if y = 13, then the point (20,13) in on the line:
Hence, the point (20,13) is on the line