Please Help for question 3,4,5,6,7

Me complete this proof! prove that a quadrilateral is a square. me with the steps for this proof.

Liz is shipping a package to her friend. the maximum weight of a medium flat-rate box is 20 pounds, including the box which weighs 6 ounces. write and solve an inequality to describe the possible weight in pounds, w, of the contents that liz will ship to her friend if she must use a medium flat-rate box. use the drop-down menus to explain your answer.

What is the name of a polygon that has four congruent sides and theses angle measures 60,120,60,120?