Concentration of two pollutants

Question

An Air sample contains 4.0 ppm (Parts Per Million) of two pollutants. The concentration of one is four times the other. what are the concentrations?

Answer 1

Assume that, Concentration of pollutant 1 is p1, and pollutant 2 is 4*p1,

So p1+4p1=4 ppm

5 p1=4 ppm

Conc of pollutant 1 is: p1 = 4/5 ppm=0.8 ppm

Conc of pollutant 2 is: p2 = 4p1=4*0.8=3.2 ppm