19. Write an equation to represent the relationship between x, the independent variable and y, the
dependent variable I need the equation

 The center of dilation is the origin (0, 0) and scale factor is 3.

Step-by-step explanation:  We are given to describe a dilation that that transforms ΔRST to ΔR'S'T', or to explain why it cannot be done.

We can see in the figure provided that both the triangles are right-angles at angles S and S'

Also, RS = ST = 1 unit   and   R'S' = S'T' = 3 units.

Using Pythagoras theorem, we have

and

Therefore, the ratio of the corresponding sides will be

Since the ratio of the corresponding sides are equal, so the two triangles are similar.

Hence, ΔRST can be dilated to form ΔR'S'T'.

The center of dilation will be origin (0, 0), because the shapes of the two triangles are same with respect to the origin.

Also, since the ratio of any two corresponding sides of the triangles is 3, so the scale factor is 3.

Thus, ΔRST can be dilated to ΔR'S'T' with origin (0, 0) as the center of dilation and scale factor 3.