Answer :
10 workers paint 10 houses in 10 days.
So . . . 10 workers paint 1 house a day.
So . . . 5 workers paint 1/2 house per day.
So . . . The same 5 workers can paint (5 x 1/2) = 2 and 1/2 houses in 5 days.
So . . . 10 workers paint 1 house a day.
So . . . 5 workers paint 1/2 house per day.
So . . . The same 5 workers can paint (5 x 1/2) = 2 and 1/2 houses in 5 days.