Inequalities
Solving an inequality is different from solving an equation.
You must remember:
When solving an inequality for a variable,
You can simplify any expression or part of an expression any time you want.  The “direction” of the inequality stays the same.
Adding and subtracting: the “direction” stays the same.
Multiplying or dividing by a positive quantity: the “direction” stays the same.
Multiplying or dividing by a negative quantity: the “direction” changes.