Your question needs some rewording. How does this sound? "Raphael paid $636 for camera during a 60% off sale. The camera's regular price is x. Find this price."
If the price is 60% lower than usual, Raphael is paying only (100% - 60%), or 40%, for the camera.
Thus, 0.40x = $636. Divide both sides of this eq'n by 0.40 to find the original price of the camera.
x = $636/0.40 = ?