Answer:
6 hours
Step-by-step explanation:
because if they work together it will be 9 hours slower than Kelsey's time alone.
not sure if correct
Answer:
13.12
Step-by-step explanation:
Answer:
Option B. 
Step-by-step explanation:
we know that
The formula to solve a quadratic equation of the form
is equal to
in this problem we have

so
substitute in the formula
Remember that

substitute

Answer:
absolutely no idea if this is right but i put the first one
Step-by-step explanation:
Maybe because you're finding the "difference" between the two numbers. We could also question why the answer to an addition problem is called sum.
Well, 'sum'body said that's what they should be called a long time ago, that's why we're using that term to call them now.