ok you get the fraction by first finding the y-intercept you get this by checking where the line passes through a point in the y line ok so the Y-intercept would be -7, now we have to find the slope, the slope is the rise over run in the graph. The slope would be 2/4 or when simplifies 1/2 the line is going up toward the left that means the slope is negative now put those numbers in a the equation y=mx+b, b would be you r y point and m your slope
so your equation would be y=-1/2x -7
Hope this helped