Answer:
The answer is C!!
Step-by-step explanation:
Let x be total hours of battery life. We have been given that battery life of Vera's phone is down to 2/5. So remaining battery life,

We have been also given that it drains another 1/9 every other hour. Now let us substitute our given information into an equation.

Now we will solve for x.


Let us convert 2/5 into minutes. We know 1 hour has 60 minutes.

Therefore, remaining battery life will be 5 hours and 24 minutes.
To find the magnitude of a vector, take the components, square them, then add them, then take the square root. This is very similar to the Pythagorean Theorem.
For your particular problem, I’ve included a picture showing how that specific calculation is done. :)
Eight is the greatest common factor because it is the last of the numbers that can go into both of those numbers.