To find the equation of the line, calculate the slope using two points. With the slope and one point, substitute them into the point slope form and simplify as needed.
Use the points (5,1) and (0, -2) since -2 is the y-intercept.
Theoretical probability is the number of desired outcomes (heads) divided by the total number of outcomes (heads or tails). The actual outcome does not affect the theoretical probability. Mark is correct.