The lengths of three sides of a quadrilateral are shown below: side 1: 1y2 + 3y − 6 side 2: 4y − 7 + 2y2 side 3: 3y2 − 8 + 5y the perimeter of the quadrilateral is 8y3 − 2y2 + 4y − 26. part a: what is the total length of sides 1, 2, and 3 of the quadrilateral? (4 points) part b: what is the length of the fourth side of the quadrilateral? (4 points) part c: do the answers for part a and part b show that the polynomials are closed under addition and subtraction? justify your answer.