Anna, ben, and cindy have m markers together. anna has a markers, and this is twice as many markers as ben has. how many markers does cindy have?

So, Anna has a markers, Ben has b markers and Cindy has c markers. 
We know that a+b+c = m.
And we know also that a = 2b. ( twice as many markers as ben has)
(Remember b is the number of Ben markers.)
The equation becomes:
2b+b+c=m.
Solving for c:

Cindy has (m-3b) markers. 

probability the spy is able to unlock the tablet on his first try.

Step-by-step explanation:

A probability is the number of desired outcomes divided by the number of total outcomes.

Desired outcomes:

1 correct password, so

Total outcomes:

Nine-digit codes.

For each digit, there are 10 possible outcomes. So

What is the probability the spy is able to unlock the tablet on his first try?

probability the spy is able to unlock the tablet on his first try.