If x is 20% of y and x is 50% of z, then what percentage is z of y?

Sure, let's solve this step by step:

1. From the first part of the question, we know that x is 20% of y. This can be written as x = 0.20y.

2. The second part of the question tells us that x is also 50% of z. This can be written as x = 0.50z.

3. Now we have two equations with x in them, so we can set them equal to each other: 0.20y = 0.50z.

4. To find out what percentage z is of y, we need to solve for z/y. So, we divide both sides of the equation by y to get 0.20 = 0.50z/y.

5. Then, we divide both sides of the equation by 0.50 to solve for z/y: 0.20/0.50 = z/y.

6. Simplifying the left side of the equation gives us 0.40 = z/y.

7. Therefore, z is 40% of y.