Answer:
(a)
Step-by-step explanation:
(a)The degree of a polynomial is the highest power of the unknown variable in the polynomial.
A polynomial is said to be in standard form when it is arranged in descending order/powers of x.
An example of a fourth degree polynomial is: 
We know the polynomial above is in standard form because it is arranged in such a way that the powers of x keeps decreasing.
(b)Polynomials are closed with respect to addition and subtraction. This is as a result of the fact that the powers do not change. Only the coefficients
change. This is illustrated by the two examples below:

The degrees do not change in the above operations. Only the number beside each variable changes. Therefore, the addition and subtraction of polynomials is closed.
Answer:
Step-by-step explanation:
-4m + 5 = -15
-5 -5
-4m = -20
___ ___
-4 -4
m=5
Answer:
vertical maybe if try it and see
Substitute -3 to x
(-3)^2 + 4(-3) + 1
9 - 12 + 1
= -2