Let p and q be the two polynomials represented by the linked list.
1. while p and q are not null, repeat step 2.
2. If powers of the two terms ate equal
then if the terms do not cancel then insert the sum of the terms into the sum Polynomial
Else if the power of the first polynomial> power of second
Then insert the term from first polynomial into sum polynomial
Else insert the term from second polynomial into sum polynomial
3. copy the remaining terms from the non empty polynomial into the