Five workers can do a job in 20 days how many days can 4 workers do the same job?

Can you guys plz answer this question in order and quickly plz i will give 30 points

If you could answer these your a life saver

If the altitude is drawn to the hypotenuse of a right triangle, then the two triangles formed are similar to the original triangle and to each other. which set of triangles shows the similar triangles created by the altitude in the diagram?