Explanation:
Given
points ( 2,12) and (1,6)
Now first calculating slope (m)
= (y2 - y1) /( x2 -x1)
= ( 12-6)/(2-1)
=6/1
=6
Now the equation of line is
y - y1 = m ( x - x1)
y -6 = 6 ( x - 1)
y -6 = 6x -6
6x -6+6 -y = 0
6x -y = 0
Which is the required equation
Hope this will help you.