2x + 11 = 15 ⇒ Given
2x + 11 - 11 = 15 - 11 ⇒ Subtracting 11 from both sides, this is the Property of Equality
2x = 4 ⇒ Carried on from the previous line of working out
2x ÷ 2 = 4 ÷ 2 ⇒ Divide both sides by 2, this is the property of division equality
x = 2 ⇒ Proved as required
