Short Answer:
Slope = 1.5
y = 1.5x + 3.75 <<<< Line.
Question AThe y intercept is between 3 and 4 1/2. Each square is worth 1.5 on the y axis. 1/2 of 1 square then is 0.75. So the y intercept in this case is 3.75 as a rough estimate.
The y intercept represents the number of victories a student can expect with absolutely no training whatever. It cannot go into the negative region. That would have no meaning at all in the outside world. There cannot be < 0 weeks of training when talking training training time.
Question BThe way to solve this part of the question is to use two well defined points.
One point would be (7.5, 15) and the other could be the y intercept since it is pretty clear. (0,3.75)
Step OneFind the slope
m = (y2 - y1) / (x2 - x1)
Givensy1 = 15
y2 = 3.75
x1 = 7.5
x2 = 0
Formula
substitute and solve
m =

m = 11.25 / 7.5 = 1.5
NoteWe are finding the point associated with the line and not the closest raw data point.
So far what we have is
y = mx + b
y = 1.5x + b
Step TwoFind b.
We already have the y intercept, but we should confirm it with the other point. b = 3.75 from Problem A.
However
y = 15
x = 7.5
y = 1.5x + b
15 = 1.5*7.5 + b
15 = 11.25 + b Subtract 11.25 from both sides.
15 - 11.25 = b
b = 3.75 which is just the answer we got for problem A
Answery = 1.5x + 3.75 <<<<
If x = 13 then just put it in the equation above.
y = 1.5x + 3.75
y = 1.5*13 + 3.75
y = 23.25 victories. Since I don't know what your choices are, I would round down to 23.