In my research the answer i got for this is that the percent error is 20% because all you have to do is divide 16 by 20 and see what percentage the number 16 is to 20 witch equals .8 or 80% then all you have to do is see that .2 or 20% is all that is need to make this whole thing equal 100% im sorry im not good at explaining things but im almost 99.99% sure that the percent error is 20% if it isnt please tell me and i can retry the problem i hope you have a wonderful day