Rust Programming

Hi, first of all sorry if it's not the place to ask (I'll delete the post if it's the case).

I started to learn Rust a few days ago and I'm currently doing the rustlings course. I'm at the exercise error_handling/errors2.rs. I've succeed to make it compile using the ? operator which I find kinda easy to understand.

My problem is the following: It's stated in the exercise that there's another solution. After looking at the hint, I know that the other solution is the use of match. I've kept looking at the docs, the examples and also StackOverflow posts but I can't make it work since I really don't understand how it's supposed to work.

pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
         let processing_fee = 1;
         let cost_per_item = 5;
         let qty = item_quantity.parse();

         match qty {
                 Ok(qty) => qty * cost_per_item + processing_fee,
                 Err(e) => Err(e),                                           
         };
}