In order to find the value of n, use the first two points (0,1) and (3,4) to find the line equation.
Use the following general formula for the equation of a line:
y - yo = m(x - xo)
where m is the slope of the line and (xo,yo) is any point in the line.
slope m is given by:
(x1,y1) and (x2,y2) are any pair of point on the line. For instance:
(x1,y1) = (0,1)
(x2,y2) = (3,4)
Replace the previous values into the formula for m:
Now, use (xo,yo) = (0,1) and replace these values into the general formula for a line, then, solve for y, as follow:
y - 1 = (1)(x - 0)
y - 1 = x
y = x + 1
The previous equation is the line which passes through the given points.
The value of n in the point (4,n) is the y coordinate of the point, which is the same that it is the value of y when x = 4. Then, by replacing x = 4, you have:
y = 4 + 1 = 5 = n
Hence, the value of n is n = 5