Yes, you combine 500mg of acetaminophen and 150mg of ibuprofen. Ibuprofen only comes in 200mg pills, so if you want to be really spot on, take the liquid stuff for kids.
Meanwhile 500mg is, I believe, more than they combine with opiates and acetaminophen does lead to death via organ failure on the order of hundreds of people a year. I was curious why they weighted the acetaminophen proportionally so much higher than the ibuprofen.