Ok, I needed an intermission for this one.

So we are left with the equation:
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definitions:
result (analog result from A/D conversion)
P (pressure in kPa)
VS (voltage supply ie 1024)
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result = VS * (((25 * P) + 271) / 6775)

So to start solving for P .....

result * 6775 = VS * ((25 * P) + 271)

(result * 6775) / VS = 25 * P + 271

((result * 6775) / VS) - 271 = 25 * P

(((result * 6775) / VS) - 271) / 25 = P

Or P = (((result * 6775) / VS) - 271) / 25

It only hurts a little when I try to figure these things out. I suppose the more you do it, the less it hurts. Or if you are a math guru, maybe this is fun. You guys are sick!