I'm back!!

Code:

0 = 0.7*(I - 10B) + 0.3*(-B)
0 = 0.7I - 7B - 0.3B
7.3B = 0.7I
I = (7.3/0.7)B = (73/7)B

Hm, it is a little off. Your number (80/7) supposes you lose 11 basic crystals on success, not 10.

By analogy, the third equation should be:

Code:

A = (3.7/0.3)I = (37/3)I

So your actual results:

Code:

99C = 75B + 24I
99C = (525/73)I + 24I
99C = (2277/73)I
99C = (6831/2701)A
[color=red]39.1449275[/color]C = A

(80/7) should be 10 + 1/.7, which should be the cost of success and the average cost of failure. I'm honestly not sure how to represent the cost of success at this point. All I have to say was that it (the 1/.3 part that applies) looked good for converting I into A.