Hello Guest. Here the correction.
Which is an equation of the line through (2,5) and (-4,-3).
x1/y1 (2/5)
x2/y2 (-4/-3)
m = (y2 - y1) / (x2 - x1)
m = (-3 - 5) / (-4 - 2)
m = (-8) / (-6)
m = 4/3
y = mx + a
P1:
y1 = m * x1 + a
5 = (4/3) * 2 + a
a = 7/3
P2:
y2 = m * x2 + a
-3 = (4/3) * (-4) + a
a = 7/3
The required function is:
f(x) = y = (4/3)x + 7/3 = 1.333x + 2.333
f(x) = y = (4x + 7) / 3
Greeting asinus: -) ! 
!
