Answer:
b=-9
Explanation:
Given that line MN passes through two points (4,3) (7,12)
Let us assume that equation of the line be y =mx+b in slope intercept form
Since it passes through (4,3) substitute in the equation to get
... i
Similarly since the line passes through (7,12)

ii-i gives
9 =3m or m =3
Substitute in i
