Just need clarification...

Here's the problem.

A plane flew from a southern city to a northern city, a distance of 900 miles, against a 30mph headwind. On the return flight, the 30mph wind became the tailwind. The plane was in the air for a total of 5 and a half hours. What would the plane's average speed have been without the wind?

Isn't it the plane's average speed would still be the same?

so?

V=d/t=900(2)/5.5

V=327.2727mph

However, I'm not really sure of this...

Would appreciate the Help.