Al ran twice as far as Bob. Split $$18\rm km$$ into two parts, one twice the other, to see that Bob ran $$6\rm km$$ and Al ran twice as far, $$12\rm km$$. 
Al ran twice as far as Bob ran. They ran a total off $$18\rm km$$. How far did Al run? 

(1) $$3\rm km$$ 
(2) $$6\rm km$$ 
(3) $$9\rm km$$ 
(4) $$12\rm km$$ 