5 persons can prepare an admission list in 8 days working 7 hours a day. If 2 persons join them so as to complete the work in 4 days, they need to work per day for
(a)8 hours
(b)9 hours
(c)10 hours
(d)12 hours
Answer
Answer (as printed): C
Explanation
Let the number of working hours per day be $x$.
Explanation as extracted from the printed page; notation may be imperfect.