Question

What is `z` in this equation `2a - z = a` ?

Answer 1

In the equation, `z` is equivalent to `a`.

Explanation:

Let's solve for `z`.

`2a - z = a`

Get the variable all by itself (isolate `z`).
Use additive inverse to add `z` to both sides.

`2a - z + z = a + z`

`2a cancel(-z + z) = a + z`

`2a = a + z`

Now we need to subtract `a` and get it on the left side.

`2a - a = a -a + z`

`2a - a = cancel(a-a) + z`

`a = z`

And we just found that `z = a`!