We'll need to determine the slope and then the equation of the line from information shown in the graph.
The slope is:
10 - 1
m = -------------- = 9/7
8 - 1
Use this slope and one point from the line to determine the equation of the line:
Starting with the point-slope equation, y-k = m(x-h),
y -10 = (9/7)(x - 8), or y = 10 + (9/7)x - 72/7
Multiplying both sides by 7 so as to eliminate the fractions:
7y = 70 + 9x - 72, or 7y = 9x - 2, or y = (9/7)x - 2/7
