 What you need to know

Things to remember:

• If we add to an x we do a subtraction.
• If we subtract from an x we do an addition.
• If we multiply and x we do a division.
• If we divide and x we do a multiplication.
• We are trying to get the $x$on its own.

When we rearrange in maths, it just means to move things around. If we rearrange for something, like $x$, this just means we are trying to get it by itself.

Rearrange the equation to get x on its own:

$$x + 3 = 12$$

Let’s think about what this is saying. This tells us that something, $x$, plus something is equal to 12. Well, that is pretty easy, we know that we have to add 3 to 9 to make 12.

$$x + 3 = 12$$

$$9 + 3 = 12$$

So, $x$ must be 9. $x=9$ But, how could we write the equation we start with so that $x$ was by itself? Well, let’s just get ride of that 3.

$$x = 12$$

But, wait, we said that $x=9$ not 12. So, how can we make the 12 into a 9? We subtract 3.

$12-3=9$

So, let’s rewrite $x=9$

$$x = 9$$

$$x = 12-3$$

Now, let’s compare this with the equation we started with.

$$x + 3 = 12$$

$$x = 12-3$$

So, all we did was move the number to the other side and did the opposite of addition, subtraction! This is how we get $x$ for other questions to, we just move the number over and do the opposite.

Rearrange the equation to get x on its own:

$$x -17 = 12$$

$$x = 12+17$$

Rearrange the equation to get x on its own:

$$x \times4 = 16$$

$$x = 16\div4$$

Rearrange the equation to get x on its own:

$$x \div9 = 4$$

$$x = 18\times4$$

Example Questions

$$x = 36\div12$$

$$x = 11\times7$$