It takes Frank 2 hours longer than Jane to carpet a certain type of room. Together they can carpet that type of room in 1(7/8) hours. How long would it take for Frank to do the job alone?

Answer 1

they each do a fraction , together the fractions add to one (the whole)

(15/8) / F + (15/8) / J = 1

(15/8) (J + F) = J * F

substituting ... (15/8) (2 F - 2) = F^2 - 2 F

0 = F^2 - 23/4 F + 15/4

0 = 4 F^2 - 23 F + 15