While working on a case Dr Watson accidentally fell down a 30ft dry wishing well. Sherlock Holmes lowered him down a rope.　　“Can you climb up?” shouted Holmes.　　“I’ll be out before you know it.” came Watson’s reply.　　But the climb wasn’t as easy as Watson had first imagined. Each hour he managed to climb 3ft—but slipped back 2ft.　　How long did it take Watson to get out