訳:What is the total number?
I answered to Duolingo "How much is the amount?", but it wrong. Duolingo corrected it to "How much is the sum?".
What's the difference between "amount" and "sum" ?
There is no difference in this context. But it is not common to phrase it that way. Common ways are: What is the amount? What is the sum? How much is the sum? How much it is?