Write a percent equation that can be used to solve the following problem: 820 is 20% of what number?

Let x be the number.

The percent equation is:
820 = 0.2x

To write a percent equation that can be used to solve the problem, we can use the formula:

Percent = (Part / Whole) * 100

In this case, we want to find out what number represents 20% of a given number. Let's call the unknown number "x".

So, the equation becomes:

20 = (820 / x) * 100

Therefore, the percent equation that can be used to solve the problem is:

20 = (820 / x) * 100