Or, as my wife (the uber-goddess of literal) would say, I'm sorry dear but you just can't do math with letters. They're letters for God's sake. You might be able to do math with words like "six" and "two" but letters like "x" and "y"? No wonder you're confused all the time.
Her son says that she, having gone to a parochial school, balances her checkbook with "nun-math".
I just say, "Yes, dear."