Weighted Percentile Calculation Help

First time poster. Have looked all over and have not been able to find a solution for what I'm looking to do.

I'm dealing with a very large data and need to calculate a weighted percentile. For example, in this sample data set below, I want to find the 25th percentile of the Value column weighted by the Qty column. Obviously, I can calculate the percentile of a single column, but when I need to incorporate the weights of the values, I get lost.

Would love some help adding in some helper columns and creating a formula that would allow me to calculate a weighted percentile. Cheers!

sampledata.PNG