Answer:
a = 15
Step-by-step explanation:
Substitute b = 12 , a = 9 into the equation
12 = 
12 =
← square both sides
144 = a² - 81 ( add 81 to both sides )
225 = a² ( take square root of both sides )
±
= a , then
a = ± 15
a > 0 , so a = 15
The answer is C
the mean is the average which is solved by adding up all of the numbers and then dividing that by how many numbers there are, 45/5 = 9
Answer:
2480 new movies
Step-by-step explanation:
1) First you need to find out how much money the 400 older movies made.

2) Next subtract that amount from the amount of revenue that the wants.

3) Divide the amount of leftover money by the amount that a new movie costs to rent

This means that in order to reach the desired amount of revenue the store must sell 2480 new movies.
If m and n are parallel, then that's like saying 3x-10 is equal to 5x-30 (or 3x-10 = 5x-30).
If that's the case, then You'll need to format the problem so you can solve for x. In order to solve this equation, we need to group all the variable terms on one side, and all of the constant terms on the other side of the equation.
So the -10, will be moved to the right side and the 5x will be moved to the left side. Also as each term that moves, it causes their signs to change.
So we now have the problem of 3x-5x=10-30. Now we can start to simplify the problem by combining like terms.
So 3x-5x = -2x and 10-30=-20 or more simply -2x=-20
Now we need to isolate the variable x so it's on a side by itself.
The easiest way to do this is simply divide both sides by 2, which gives us 2x/2=20/2 or more simply, x=20/2.
So we're down to the simple problem of x=20/2 which equals 10. So x=10.