the answer i got was 5% , because all you have to do is perform a proportion . you put $400 which is what avery made over the total money of the sale which is $8,000 . then you put n the variable over 100 so you can find the percentage of her commission . now you have to cross multiply , so you would multiply $400 and 100 . & $8,000 with the variable n . in the end you'll get 400*100= 40,000 and 8,000n= 8,000n . now you would divide 40,000 by 8,000 to get rid of the 8,000 off the variable . so 40,000/8,000= 5 . so the percentage of her sale is actually hers is only 5% .