Question 655298
assume that they took 'x' days to clean the house together.
as Mrs. brawn cleans in 3 hours. in 1 hour she cleans 1/3rd part of the house.
hence in 'x' hours she cleans x/3 rd part of the house
similarly her daughter cleans the house in 6 hours. in 1 hour she cleans 1/6th part of the house.
it means in 'x' hours she cleans x/6th part of the house.

both of them paints '1' house is 'x' hours.

hence equation becomes:  {{{(x/3) + (x/6) = 1} multiply both sides by 6

                         {{{(2x) + (x) = 6}}}

                          {{{3x = 6}}}

divide both sides by 3    {{{3x/3 = 6/3}}}
                           x = 2
Mrs. Brawn and her daughter can clean the house in 2 hours working together.