Given that RT ≅ WX, which statement must be true?

RT + TW = WX + TW
RT = 2(RX)
WX = 2(RX)
RT + TW = RX

The statement that must be true is:

RT + TW = WX + TW

The statement that must be true given that RT ≅ WX is WX = 2(RX).