Add to Both Sides

$$3 < 7$$

Add 10 to both sides: $13 < 17$. This is still true. Subtract 10 instead: $-7 < -3$. This is true too, because -7 is further below zero than -3.

Adding or subtracting the same number on both sides keeps an inequality true. The sign stays the same.

So you can solve an inequality like an equation.

$$x-4 > 3$$

Add 4 to both sides.

$$x > 7$$

Check with 10: $10-4 = 6$, and 6 is greater than 3.