Biochemistry question: Protein subunits/polypeptides?

Hi, I've been working on a practice test problem and can't seem to figure it out, can someone try to help me? Thank you in advance:

Consider the following about protein A: Each protein “A” consists of two subunits of polypeptide “B”, and four subunits of polypeptide “C”. Each polypeptide “B” consists of two polypeptides of “D”, one polypeptide of “E”, and six polypeptides of “F”. Each poly polypeptide of “C” consists of one polypeptide “E”, and one polypeptide of “F”. How many polypeptides of “E” are necessary to produce a single final protein A?