(i) Our point C to be plotted lies on function y = 3x.

Here, first plotting y = 3x.

Here, x = 3.

∴ Now for abscissa equal to 3, we plot the point on y = 3x, ie y = 3 × 3 = 9

Hence, the value of y is 9

(ii) Our point to be plotted lies on function y = 3x.

Here, first plotting y = 3x.

Here, x = 5.

∴ Now for abscissa equal to 5, we plot the point on y = 3x, ie y = 3 × 5 = 15

Hence, the value of y is 15

(iii) Our point to be plotted lies on function y = 3x.

∴Here, first plotting y = 3x.

Here, x = 6.

∴ Now for abscissa equal to 6, we plot the point on y = 3x, ie y = 3 × 6 = 18

Hence, the value of y is 18