Question

How do you solve `13-4x < 25`?

Answer 1

`x > -3`

Explanation:

`13 - 4x < 25`

Add `color(blue)(4x)` to both sides:
`13 - 4x quadcolor(blue)(+quad4x) < 25 quadcolor(blue)(+quad4x)`

`13< 25 + 4x`

Subtract `color(blue)25` from both sides:
`13 quadcolor(blue)(-quad25) < 25 + 4x quadcolor(blue)(-quad25)`

`-12 < 4x`

Divide both sides by `color(blue)4`:
`(-12)/color(blue)4 < (4x)/color(blue)4`

`-3 < x`

Therefore,
`x > -3`

Here's a graph of it on a number line:

(mathwarehouse.com)

The open circle on `-3` means that it is not a solution (but anything greater than it is).

Hope this helps!