Given the following question:
To write the graph as a equation we will use the formula for slope intercept
y = mx + b
First find the y intercept:
y = 700
x = 0 (x always equals zero)
b = 700
Which means the options are rather A or B since b = 700
Now we have to find the slope, the slope is the change of y divided by the change of x:
x = -3
Your answer is option A or y = -3x + 700