[lparis]

ABS plastic is a tough, hard plastic used in applications requiring shock resistance. The polymer consists of three monomer units: acrylonitrile (C3H3N), butadiene (C4H6), and styrene (C8H8).
a. A sample of ABS plastic contains 8.80% N by mass. It took 0.605 g of Br2 to react completely with a 1.20-g sample of ABS plastic. Bromine reacts 1:1 (by moles) with the Butadiene molecules in the polymer and nothing else. What is the percent by mass of acrylonirile and butadiene in the polymer
b. What are the relative numbers of each of the monomer units in this polymer

I tried using %mass formula (g acrylonitrile/total mass of polymer)x100 but it doesnt seem to be right. Not sure wher I would use the %N in the calculations?

[Borek]

Nitrogen is present only in acrylonitrile, so it gives you information about A amount. C is what is left after you know both A & B.