Using substitution:
first you have to express one variable in terms of the other, in this we can express y in terms of x:

Since both expressions are equal to y, you have to equal both expressions like this:

Now you can solve the equation:

Knowing x=10, you can use any of the expressions we found before to find y. In this case I'm going to use y= -x+9 because it's simpler but boy should give you the same result

So, the answer is x=10 and y=-1
Answer:
False
Step-by-step explanation:
The statement is False, because the average value of a funciton f(x) on an interval is given by the value of the integral of the function on that interval divided by its length. In this case, the integral is right, but we are not integrating exactly f, and thats why the average value is not given correctly.
Answer:
The mean of the sampling distribution of p is 0.75 and the standard deviation is 0.0306.
Step-by-step explanation:
Central Limit Theorem:
For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean
and standard deviation 
75% of teenagers in North America are pursuing a goal they have set for themselves.
This means that 
Sample of 200.
This means that
.
What are the mean and standard deviation of the sampling distribution of p?
By the Central Limit Theorem
Mean 
Standard deviation 
The mean of the sampling distribution of p is 0.75 and the standard deviation is 0.0306.
B, because it actually has the number of sponsors and is a positive slope.