Question 251288
We know that 
R(0,2), S(6,-4), and T (-4,-12). 
Applying a scale factor of 1/2, we get
R'(0,1), S'(3,-2), and T'(-2,-6).

The slope of ST = slope of S'T' = 4/5.
The Y-intercept of S'T' = -22/5.
The Y-intercept of ST = -44/5.

I don't see anything wrong with your answer. Is it possible that the "real" answer or book answer is incorrect?