Answer:
12
Explanation:
If Q is the midpoint, that means the distance from both P to Q and R to Q must be equal. Set the equations to be equal to one another.
x + 9 = 4x
Subtract x from both sides
3x = 9
x = 3
Now, substitute 3 for x again and put it into one of the equations. It doesn't matter because the answer will be the same.