Prefix Notation

I could do with some prefix notation practice (I have not reached Satori).

To this end, I'd be terribly obliged if you could post some nested mathematical expressions with nested brackets and only simple (+ - * /) operators, so I can practice converting them.

I'd also be obliged if you could tell me if I'm right/advise me where I'm going wrong.

An example;
7(8 x 9(10 x 3(8 + 4)))
(* 7 (* 8 (* 9 (* 10 (* 3 (+ 8 4 ) ) ) ) ) )

Am I right? Wrong? Advice?

>>2
So, technically right, just need to clean it up? Thank you very much :D

A supportive IRC-er gave me a monster one to solve - namely
(6(9-8*2(4-5)+7-4(2*3)+4-8))/(5(3(7-3)(2+1)-8+9-4))

With my shitty, uncleaned-up code, I got
(* 6 (+ (- 9 (+ (* 8 2 (- 4 5 ) ) 7 (* (- 4 (* 2 3 ) ) ) 4 (- 8 ) ) ) ) (/ (* 5 (* 3 (+ (- 7 3 ) (+ 2 1 ) (- 8 ) 9 (- 4 ) ) ) ) ) )

Let me just clean it up and I should be able to figure out if I'm right - the REPL says the answer is 12/5