Some physics/math help

[ParkerF]

I'm a part of the Texas High School Aerospace Scholars program, an online science course that the Johnson Space Center is conducting. All of the lessons consist of an essay, math problem, and occasionally a graphic. The first lesson doesn't quite explain the math problem that well, and many of the other students are confused. I can't simply tell you the full question because I'm supposed to be doing this myself, but I just need clarification as to what it's asking for.

If an orbiting craft needs to reduce its perigee to a certain altitude from its current altitude, how would I find the change in velocity the craft must make? I'm provided with both the initial and final distances, along with the mile:fps change in velocity ratio for these altitudes. Two of the other students have mention the Braking Distance formula of Vf^2=Vo^2+2ad, but I don't see how to use it.

Any help at all would be appreciated.

Thanks much,
Parker