Adding and Subtracting Polynomials

Identify the degree of the polynomial: $$4x^2-x+14$$

Identify the degree of the polynomial: $$-2x+4$$

Identify the degree of the polynomial: $$x^4+9x^3-2x-7$$

Add the polynomials: $$(4xy-2x-3y)+(6y+6x+5xy)$$

Add the polynomials: $$(5rt-3rw-8tw)+(6rt-4rw+2tw)$$

Subtract the polynomials: $$(2a^2+5a+3)-(a^2-3a-4)$$

Subtract the polynomials: $$(4n^4-8n+4)-(8n^2+4n^4+1)$$

Subtract the following polynomials: $$(6x^2+10x-9)-(4x^2-13)$$