Question

How do you solve `14+ c = 20`?

Answer 1

`c = 6`

Explanation:

Given an equation that is supposed to be true, if you do the same thing to both sides of the equation then the resulting equation will also be true.

If what you do is reversible - such as adding or subtracting the same value on both sides - then the first equation is true if and only if the second is true.

Given:

`14+c=20`

We can subtract `14` from both sides to find:

`c = 6`

`color(white)()`
A little slower...

On the right hand side:

`20 - 14 = 6`

On the left hand side:

`14+c-14 = c+14-14 = c+0 = c`

So subtracting `14` from both sides turns:

`14+c=20`

into:

`c = 6`

Conversely, given `c=6` we could add `14` to both sides to get our original equation. So this is a valid solution to the original equation.