Revising for a exam by doing some past paper and i need help with this question.

You are given a stereo configuration with the following parameters: the
baseline is 20 cm, the focal length is 8 mm, a pixel is 0.02 mm square, the
images are 256x256 pixels with center C at [128, 128]. A feature point A
in the scene appears in mAL(160, 120) and mAR(130, 120) on the left and
right images respectively. Use the formulas below for your calculations.

http://img704.imageshack.us/img704/7793/

-Compute the disparity in millimeters.
-Compute the 3D coordinates of feature A.

Thanks for looking. If i just knew how to do this example then i would find it a lot easier in the exams!

Cheers
Pk