What is the sum or difference?
a. 5x4 + 4x4
b. 12x5y − 9x5y

a. 9x^4

b. 3 x^5y

Step-by-step explanation:

a. 5x^4 + 4x^4

Combine like terms

9x^4

b. 12x^5 y − 9x^5 y

Subtract like terms

  3 x^5y

(x , y )  > (x , y -4)

Step-by-step explanation:

There is no change in x-coordinate

Compare the y-coordinate of A(-4 , 7) and A'(-4 , 3)

7 + a = 3

    a = 3 - 7

   a = -4

y-coordinate of A' = y-coordinate of A  - 4