Hi There,
You can use the newly added functionality Invoke Custom Function in the Query Editor for this and It would be more creative solution as you can use them for other type of similar tasks as well.
To do so,
1.Add a Blank query and Write the below code:
(Qscore as number, Rscore as number,Sscore as number) => Qscore + Rscore + Sscore
Note: Change the Code as per your requirement as your calculation are different than shown here.
2. Go to your original query and Under the Add Column Tab, Select Invoke Custom Function.
and Choose the appropriate options and it will give you desire results.
OR
You can use custom column in the query editor to achive the desired results.
Let me know if you get stuck.