In the following figure, rectangle represents brand managers, circle represents cartoonist, triangle represents sculptors and square represents fathers. Which set of letters represents fathers who are either brand managers or cartoonists?
A boat goes 15 km upstream and 10 1/2 km down stream in 3 hrs 15 min. It goes 12 km upstream and 14 km downstream in 3 hrs. What is the speed of the boat in still water?