The slope of the line appears to be about 30/4 = 7.5. Since it starts at y=10 for x=0, the equation of the line is
y = 10 +7.5x
For x=7, the value of y (Linda's score) will be
y = 10 + 7.5*7 = 10 + 52.5 = 62.5
Linda's approximate math score for 7 hours' study will most likely be
62.5 points
