It takes ten workers ten days to paint ten houses. How many houses can five workers paint in five days?

5 workers paint 2.5 houses in 5 days.

Step-by-step explanation:

10 workers paint 10 houses in 10 days.

1 worker is 1/10 the workforce of 10 workers, so:

1 worker paints 1 house in 10 days.

1 worker paints 0.5 house in 5 days.

5 workers are 5 times the workforce as 1 worker.

5 workers paint 2.5 houses in 5 days.