Let v be the speed of the slower plane in mph.
Then the speed of the faster plane will be (v + 55) mph.
the closing speed of the two planes is the sum of their speeds:
v + v + 55 = 2v + 55
[tex]time=\frac{distance}{speed}[/tex]
[tex]3=\frac{1965}{2v+55}[/tex]
Cross-multiplying, we get:
6v + 165 = 1965
6v = 1800
v = 300
The speeds of the planes are 300 mph and 355 mph.