I really need help please yong ma ayos

1.
Sum: 5h-3
Difference: -x+9
2.
Sum: 18p²+8r+5
Difference: 4p²+8r-5
3.
Sum: 7x-15y+13z
Difference: x+3y-7z
4.
Sum: -w²
Difference: 14w³-5w²+2w or w(14w²-5w+2)
5.
Sum: 27mn³-6m²+8mn-n
Difference: 19mn³-8m²+8mn+n