Answer:
1.) Polynomials are added or subtracted by changing the signs (when needed) and adding/subtracting like terms
2.)161
3.)cz
Explanation:
2.) 81^2-80^2
(81+80)(81-80)
161x1
161
3.)ab/c + xy/z = abxy/cz thus, the common denominator is cz
Hope this helps, hope your call goes well :)