Graph using Maple for Astronomy

[I Am Robot]

Homework Statement

I am not sure what to do with Maple. I've barely used it at all, but trying to figure out why this won't work with what I have below.

Plot schematically the change in equilibrium temperature of Earth, if its albedo changes from 0.3 to 0.7 (in 0.1 jumps).

Homework Equations

$\frac{L(1-a)R^2}{4d^2}$

The Attempt at a Solution

(This assignment is old btw, just wanted to figure out what I did wrong.)

When I right click on the equation and select plot it assigns my already assigned variables as unknowns between -5 and 5. Really not sure what to do?

[PLAIN]http://img838.imageshack.us/img838/4474/maplef.jpg

Did I improperly assign the variables or perhaps the function?

 

[Spinnor]

I can't help but did you try here? Its free.

http://www.maplesoft.com/studentcenter/forum.aspx