Mathematics for IGCSE & O level - Inequalities (Section 1 - No. 46)
What do we do to both sides of the equation to keep the equation true, which is also the same for inequalities?
Always add a constant
Always subtract a constant
Always subtract a variable
Do the same thing to both sides.
Paliwanag
As long as you perform the same operation on both sides, the equation (or inequality) remains valid.