The speed to the island is x. The speed to return is x+5.
The distance is the same so, 2.5 multiplied by x = 2×(x+5).
It took 2.5 hrs to get there and 2 hrs to return. Now all we have to do is solve.
2.5*x = 2x + 10
.5x = 10
x=20
Therefore, the distance between islands is 2.5 × 20 = 50 miles.
hope this helps!
