Which phrase can be represented by an equation? twice as much as a number 12 less than a number half of a number is 15 the difference of 20 and a number

Half of a number is 15

Step-by-step explanation:

First of all, add commas between each option so it's easier to read I had a hard time figuring out what the options were because of this.

An equation is a statement that the values of two mathematical expressions are equal. An expression is a collection of symbols that jointly express a quantity. This means there has to be an equal sign when the phrases are put into numerical form.

Twice as much as a number:              2X

12 less than a number:                        X - 12

Half of a number is 15:                        X/2 = 15

The difference of 20 and a number: 20 - X

As you can see, only one of these phrases is an equation by definition, and that is X/2 = 15, or half of a number is 15. That's because it's the only one that values two expressions as equal.