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# Rearranging equations

We can express an equation in terms of the other variable.

For example, $P = 16 - 2Q$

To rearrange the equation so that it is written as $Q=$ take each term and move to the other side of the equal sign using the opposite operation until you only have $Q$ remaining on the left.

e.g. Rearrange $P = 16 - 2Q$ to make $Q$ the subject of the equation

$P = 16 - 2Q$

$P+ 2Q = 16$     Take $-2Q$ to the other side of the equal sign by adding $2Q$ to both sides

$2Q = 16 - P$     Take $P$ to the other side of the equal sign by subtracting $P$ from both sides

$Q = \frac{16-P}{2}$           Divide both sides by $2$

Now if we have a value for $P$ we can find $Q$

e.g. Find $Q$ when $P=6$

$Q = \frac{16-6}{2}$ $Q= 5$