Let C(p) denote the cost of producing a book with p pages. Suppose that each page added to a book increases its production cost by $0.04 and that a 100 page

C(p)  =  .04p  + F       where F is the fixed cost  [ the cost we incur no matter how many pages are produced ]......so we have

6.00  = .04(100) + F      simplify

6.00 =  .40 + F    subtract ,40 from each side

5.60  = F     so.....the fixed cost per book = $5.60      and the general formula for the cost to produce each book is given by :

C(p)  = .04p + 5.60

Sorry to contradict the previous post, however, 0.04 multiplied by 100 is 4...not .4, as such the answer would come out to be b = 2. Plug in for y = mx + b and you should end up with y = .04x + 2