Can you please help me with this problem, its really hard..

Could answer every question with steps

5. which description does not guarantee that a quadrilateral is a squar ajo is a parallelogram with perpendicular diagonals 0% has all sides congruent and all angles congruent o has all right angles and has all sides congruent 10% is both a rectangle and a rhombus 30%

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9