lets first find the slope of the line passing through those points. A(3, 2), B(7, 8) all we have to do is divide the y portion over the x segment:
m = (8 - 2)/(7 - 3) = 6/4
m = 3/2
that is the slope of the line
And now lets use the line equation for slope and one point A(3, 2)
y - y1 = m(x - x1), where x1, y1 are the coordinates of a point of the line, A in this case:
y - 2 = (3/2)(x - 3)
y = (3/2)x - 9/2 + 2
y = (3/2)x - 5/2
