we can calculate the rate of change of a line (slope) by means of the following formula:
[tex]m=\frac{y2-y1}{x2-x1}[/tex]
Where (x1, y1) and (x2,y2) are two points of the line.
From the given graph, we can see that the line passes through the points (4, 300) and (8,600), by replacing these values into the above formula, we get:
[tex]m=\frac{600-300}{8-4}=\frac{300}{4}=75[/tex]
For a linear equation, its slope is the number that multiplies the variable x, from the given options, the only equation that has a slope greater than 75 is the second one, with a rate of change of 85.
Then, the answer is the second option y=85x
