Question 353728
From the equation {{{S/6=74}}}, we get {{{S = 444}}}, the sum of all his scores from the 6 exams.  let x = his score on the 7th exam.  Thus,
{{{(444 + x)/7 = 80}}}.  (Note that he has to get an 80 out of an hundred to get a B.)
{{{444+x = 560}}}.
{{{x = 116}}}.  
Therefore he has to get 116 out of 100 in his last exam, which is impossible (at least on paper! haha)