You can just divide the 54 by 6 to get the single cost, since it gives a constant rate (possibly not, but most likely since it doesn't mention taxes, tips, ect.)
The unit rate is 9 bucks per pizza.
I have no idea why we would use links in the first place.
You will have to find 6% of 550. As a proportion it will look like... 6/100=x/550 550*6=3300 3300/100=33 x=33 33 toys will be defective. Hope I was of assistance.