MySQL question to ask

[Dart]

Dear all,
Sorry to ask question again, or maybe i am just a beginner.

I wanna ask:
If there are 2 records
Name             Income      Out
Data1               1000       700
Data2                970        500

If i want to have the output:
Name              Income      Out      Balance
Data1               1000          700       300
Data2                970           500        770

How to do that?
Thx!!!!!!!!

Yours sincerely,
Jason Chan