+273 Deven has four ducks labeled A, B, C, and D. How many ways are there for Deven to arrange his ducks in a row if duck A must be before duck D?
+37159 Could be ADxx AxDx AxxD xADx xAxD xxAD six ways for A before D
the other two slots have two ways to arrange
6 x 2 = 12 ways
