Question on combat values and fire values

[melm]

In my understanding, 152 is fire value not combat value. Combat value comes from fire value (in manual it uses the word 'adjusted') while I don't know the formula and this is the key problem I have. Correct me if I am wrong. However, casualty is based on calculation of combat value not fire value from the example manual gives. That's why I am eager to know how to get the number for the combat value.