Question

A fathom is 6 feet how many feet deep is water that is 2 1/2 fathoms

Answer 1

1 fathom = 6 feet

2 1/2 fathoms = x feet

2 1/2 fathoms • 6 feet = x feet

x = 15

2 1/2 fathoms = 15 feet

Answer 2

You just do 2 * 6, which is 12, 
then 1/2 of a fathom, or 6 is 3
so, add 3 to 12 to get 15.

2 1/2 fathoms = 15 feet.