For example, you're having an exam of multiple segments, and somebody comes over and says "Hey, mate, what's your total?" and you're like "Oh yeah, it's 95 points". Or something like that...
Imagine closing up shop and you are counting the cash in the register(s) and your boss asks how much money there is in total.
Non ho la certezza ma penso che non si deve usare «qual'è», invece «qual è» è corretto. «Quale» si usa in tutti gli altri casi: «Quale torta ti piace?» ma fa attenzione agli sostantivi che cominciano con una vocale: «Qual ombrello ti piace?»
Can someone please explain the difference/similarities between "Cosa" "Che"and "Qual" ???
Cosa means "what", "Che" can mean both "what" and "which" and "Qual" means "which".
For example: "Che cosa prende?" (is the correct form, whereas only "Cosa prende?" would be the abbreviated, colloquial form. "Che lavoro fa?" is also possible, instead of "Qual lavoro fa?".
«Qual» does not mean "what;" it just translates to "what" in this context. English just happens to not use "which" in these contexts, unlike so many other languages. Think of it this way: the total can be any number in a set of numbers. The person asking is just trying to figure out which, out of all the possibilities, the total actually is. It can only be so many things; it's not completely open-ended.
According to A Reference Grammar of Modern Italian (2nd ed), by Maiden & Rogustelli (2013),
"Quale?" is a pronoun or adjective used to request identification: possible replies to it would contain a name, a demonstrative (questo, quello), or even just the act of pointing to the relevant entity. It corresponds not only to English ‘which?’ or ‘which one?’ but also, sometimes, to ‘what?’
In contrast, "che?", and the pronouns "che?" or "che cosa?" request not necessarily identification (although they have this function, too) but definition or explanation.
The appropriate answer to "Qual è la capitale della Polonia?" [What is the capital of Poland?] would be "Varsavia", [Warsaw].
But the answer to "Che cos'è la capitale della Polonia?" [What is the capital of Poland?] one might equally reply, "È uno dei più importanti centri commerciali dell'Europa orientale" [It's one of the major commercial centres of eastern Europe]."
'They charged me twenty dollars for this lot! What is your total?' 'Same!'
Still, it's kind of weird isn't it. I've never said those words to anyone.
We wouldn't say it. When What can be Which or Who, I think we prefer to translate it as "Quale" or "Quali"