Question 798793
A fairy leaves a harbor and travels at an average speed of 16 mph.
 Because of the fog the fairy returns traveling at an average speed of 12 mph.
 The total time for the trip was 7 hours.
 How far is the island from the harbor?
:
I think you mean "ferry", but anyway;
let d = the one way distance to the island
write a time equation, time = dist/speed
:
{{{d/16}}} + {{{d/12}}} = 7
multiply eq by 48
3d + 4d = 48(7)
7d = 48(7)
divide both sides by 7
d = 48 miles to the island
:
:
Check by finding the time each way
48/16 = 3 hrs
48/12 = 4
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total: 7 hrs