For this case we have that by definition, the point-slope equation of a line is given by:

Where:
m: It's the slope
b: It is the cut-off point with the y axis
We have two points:

We found the slope:

Thus, the equation is of the form:

We substitute one of the points and find "b":

Finally, the equation is:

Answer:

Yes, they are proportional. if you divide the second fraction down to simplest form, you get 7/12, which is equal to the first fraction.
Y=3.5x+4
a) 5=3.5x+4, 3.5x=1, x=1/3.5=2/7
b) y=3.5*10+4=35+4=39