# Subject of a formula

Subject of a formula – It is the variable everything is equal to (it’s the letter on its own).

Todays **subject** will be how to write a **letter.**

**Example 1**

`x=2y+4z`

‘x’ is the subject of the formula because it is the LETTER everything is equal to.

**Example 2**

Rearrange the following equation to make `C` the subject.

`A = BC-3D`

**Answer: **`C=(A+3D)/B`

Now `C` is the subject of the formula.