gradient and equation of straight line...?

Question

if there are two points, A(0,2) and B(12,6) on a straight line how do you show that the equation of the line AB is 3y-x=6?

Answer 1

well its simple.
first you need to know the gradient which is

change in y/change in x= (6-2) /(12-0) which is 1/3
using the equation y=mx+c and chosing either A or B you can find c

using B(12,6)

6=1/3(12) + c
6=4 +c
6-4= c
2= c

and so the equation will be
y=1/3x +2

to remove the fraction multiply everything by 3
3y=x+6
3y-x=6

Answer 2

The sloe is

M=(6-2)/(12-0)=1/3 and the intercept is the point A(0,2)
The equation would be y=1/3x +2
Or 3y-x=6

Answer 3

I dont know