Answer:
Step-by-step explanation:
Let x be the speed of first ferry.
Then the speed of second slower ferry is x-5 (since 5 miles per hour slower)
Time taken by first ferry = distance/speed = 
Time taken by second ferry = 
Since second ferry starts one hour early, difference in times is 1 hour.

Speed cannot be negative.
Hence answer is speed of the first ferry = 18.5 mph
and second ferry i.e. slower ferry is = 13.5 mph
Is there anymore information?
If the plane descends entirely to the airport runway then it would be zero.
If you would like to solve 16x^2 - 81 = 0, you can calculate this using the following steps:
<span>16x^2 - 81 = 0
</span>(4x - 9) * (4x + 9) = 0
1. 4x - 9 = 0 ... 4x = 9 ... x = 9/4
2. 4x + 9 = 0 ... 4x = - 9 ... x = - 9/4
The correct result would be: <span>x = 9 over 4, x = −9 over 4.</span>