EXAM TOMORROW .ANSWER IMMEDIATELY!!!!!!!!!!!

Let x be the work done by a man in one day, and y be the same for a woman,

1 piece of work = 6(6x + 5y).............1/6 = 6x + 5y

1 piece of work = 10(3x + 4y)...........1/10  = 3x + 4y

Solving these simultaneously we find,

x = 1/54, y = 1/90

 

Hence,

1 piece of work = D(9x + 15y)

where D is the number of days required as in the question.

D = 1/(9(1/54) + 15(1/90)) = 3 days.

Regards,

Team,

TopperLearning.