In order to make an equation with infinitely many solutions, you basically need to have the same thing on the left and right side of the equation. This way, no matter what you plug in for x, the equation is true.
The given equation is Px + Q = 46x + 23.
What can we plug in for P and Q to have Px + Q equal 46x + 23?
The answer, as you may have guessed, is P=46 and Q=23.
Now plug into the function:
46x + 23 = 46x + 23. No matter what you plug in for X, your equation will hold true. This function has infinitely many solutions, and for that reason, is pretty much useless.