Explanation:
1. First calculate for the gradient m
2. Calculate for the constant C by using any point (0,3) or (3,9)
3. Lastly, put the values found in the equation y = mx + c
1. m = Y2-Y1/X2-X1
=9-3/3-0=2
2. input one point together with m into the equation y=mx+c
3=2(0)+C
C=3
3. Therefore equation of linear relationship is
y = 2x + 3