After a decimal and its own addition, subtraction and division, the sum of sum and difference quotient is 10.4. What is the original decimal?

After a decimal and its own addition, subtraction and division, the sum of sum and difference quotient is 10.4. What is the original decimal?

If subtraction equals 0 and division equals 1, then twice the number equals 9.4, so the number is 4.7