The 250 minute plan is best for her. The reason is 1470/6 is 245 which is a little less than that plan. Working for Kate's needs
Answer:
C. 4.2a + 0.8
Step-by-step explanation:
Given:
The two binomials given for addition are:
and 
Now, adding both the binomials, we get:

Distributing the positive sign inside the second binomial, we get:

Now, combining like terms using the commutative property of addition, we get:

Simplifying the above expression, we get:

Therefore, the resulting addition of the given binomials is 
Hence, option C is the correct answer.
The main property is as follow
(A^p)^q=A^pxq
so only Sam's work is correct because
(8^4)^5 x(7^3)^9=(8^4x5)x(7^3x9)=8^20x 7^27