Creating a formula while isolating one part of the information in a row

[JablesFTW]

Hey all. New to the board. I'm not horrible at formulas, but this one is stumping me.

I need to create a formula to find a percentage total based off of two columns, however one column has multiple numbers and I need to isolate only one.

So, here's what I'm working with:

Column J (quantity) has my total build. Column L (customer_breakdown) has a breakdown of different types. Those types combined will equal the total in Column L.

quantity	customer_breakdown
500​	R: 45 (50), L: 53 (75), L1: 56 (75), SNS: 50 (50), L2: 50 (50), L3: 50 (50), L4: 25 (25), L5: 25 (25), P: 146 (100)

How can I create a formula that isolates "P: 146" only, compares it to the total of 500 in "quantity" and spits out the percentage in a new cell next to it?

I'll be having to do this for 100+ different rows each week, but if I can get the formula I can just drag down the formula. The info will always change, but the formatting will always be the same.

Thanks!

 

[steve the fish]

Like this?

=TEXTBEFORE(TEXTAFTER(L1,"P: 146 ("),")")/J1