Step-by-step explanation:
eqn of line : y = mx+ c
m = slope or gradient
c = y-intercept.
Lets take (1,6) = (x1,y1) and (2,3) = (x2,y2)
[tex]m \: = \frac{y1 - y2}{x1 - x2} \\ = \frac{6 - 3}{1 - 2} \\ = \frac{3}{ - 1} \\ = - 3[/tex]
Substitute x = 1 and y = 6 into equation,
[tex]6 = ( - 3)(1) + c \\ 6 = - 3 + c \\ c = 6 + 3 \\ = 9[/tex]
Therefore substituting m and c value, equation of line is
[tex]y = - 3x + 9[/tex]