How do I set average number from other points

I have VariableA and VariableB

every time when i start play game timer is start

every 1second add to variableA + 1

When i need quit i click submit and i send this value of VariableA to variableB

But every time when i do this variable B should show average of all added varlues

You can't store an average in one variable. You need to store each variableA when you quit, so that you can take the average of all of the values.

blackhornet so i must create multiple variables for this?

You need an array. Then store the array. OR, you need two variables. One for the sum (variableB), and one for the number of times the sum has been added (variableC). Then your average is variableB/variableC.