The equation in point slope form is 
y-4 = (1/2)(x -2). 
The equation for point slope form is 
y - y1 = m(x - x1)
The point on the graph is given as (2,4) so you can substitute that into the equation as 
y - 4 = m(x - 2)
M represents the slope. 
By looking at the graph, you can see that the y-intercept is (0,3). The slope is change in y / change in x or the rise/run. From (0,3) to (2,4). 
Change in y = 4 - 3 = 1
Change in x = 2 - 0 = 2
Therefore the slope = 1/2 = m. 
Substitute m in for the slope and the final equation in point slope form would be y-4 = (1/2)(x -2).