Which of these is an example of a random sample? A.
Customers buying a new cell phone are surveyed about cell phone plans.

B.
A phone plan company surveys people on the beach to see how well they are receiving service, and uses this information in future advertising.

C.
Every twentieth caller to an independent radio station receives tickets to a concert.

D.
A phone survey is conducted using twenty names randomly taken from the phone book.

The random sample is D. The other 3 cannot be taken as random since they involve groups at a specific place or doing a specific thing.

Step-by-step explanation:

idk

step-by-step explanation:

idk

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.