Question

How do you solve for x in `y=5x+9`?

Answer 1

`x = (y-9)/5`

Explanation:

In these problems, we want to get `x` all by itself on one side of the equation and everything else on the other side. That's when we can say we've solved for `x`. So, we'll start by moving the 9 to the left side of the equation by subtracting it from both sides:

`y = 5x+9`
`y-9 = 5x+9-9`

We can see that they cancel out, since `9-9 = 0`:

`y-9 = 5xcancel(+9-9)`

Now, all we have to do to get `x` by itself is to get rid of the 5 next to it. We do this by dividing by 5:

`y-9 = 5x`
`(y-9)/5 = (5x)/5`

Because `5/5 = 1`, the fives cancel:

`(y-9)/5 = cancel(5/5)x`

To finish, we state our solution:

`x = (y-9)/5`