There are so many parts to this question that I would normally skip it ...
I mean, even though there are only 4 letters, it needs 7 answers.
But I was so overcome with shock and awe at the sight of the bountiful
5 points at the end of the rainbow that I just couldn't pass it by.
Tim can paint a house in 6 days.
Tara can paint a house in 3 days.
a). Tim paints 1/6 of a house in one day.
Tara paints 1/3 of a house in one day.
b). In 'd' days, Time can paint d/6 of a house.
In 'd' days, Tara can paint d/3 of a house.
c). In one day, Tim and Tara together can paint (1/6 + 1/3) = 1/2 of a house.
In 'd' days, Tim and Tara together can paint (d/6 + d/3) = d/2 of a house.
d). The number of days it will take Tim and Tara together to paint
a whole house is
N = 1 / (1/6 + 1/3)
N = 1 / (1/2)
N = 2 .