Answer:
-4 1/2 or -4.5 or -9/2
Step-by-step explanation:
we have been asked to perform 
The given expression can be written as

Now it can be re-written as below

Answer:
4
Step-by-step explanation:
RS + ST = RT
=> 3x-8 + x = 2x
4x - 8 = 2x
Subtract 2x from both the sides,
4x - 2x - 8 = 0
2x - 8 = 0
Add 8,
2x = 8
Divide by 2,
x = 8/2 = 4
Length of line segment ST = x = 4