AICC score divide by 4

I have 4 tests in one AU and when I want to display the results it gives the total of all tests eg 400%. But what I want is too devide this score by 4. In this way I get the average of the 4 tests.I've tried it by making a 'var(devide4)' and an action 'on show' > Modify Var > target: AICC_Score ;value 'var (devide4)'..but what now? What do I choose for 'Modification Type'?Also I don't know what to put in the 'initial value' field for my 'var (devide4) '.I hope my writing makes sense :-)or am I all thinking the wrong way arround?