1)
Take into account that the equation of a line can be written as follow:
y = mx + b
where m is the slope and b the y-intercept.
the slope can be calculated as follow:
m=(y2 -y1)/(x2 - x1)
where (x1,y1) and (x2,y2)
For the given graph, consider the points (0,3) and (4,4)