Which value of x makes this inequality true?

X + 9 < 4x

We want to get out x's together on the right side of the inequality.

So, subtract x from both sides to get 9 < 3x.

Now divide both sides by 3 and we get 3 < x.

I personally like to have my variables on the left so we can move the 3 to the left and the x to the right but if we do that, we have to switch the inequality sign.

So we can rewrite this as x > 3.