12 is 40 percent of what number?

To find the number that 12 is 40% of, you can set up a proportion. Let x represent the unknown number. The proportion would be: 12/x = 40/100. Cross multiplying gives you: 12 * 100 = 40x. Simplifying further, you get: 1200 = 40x. Dividing both sides by 40 gives you x = 30. Therefore, 12 is 40% of 30.