Answer:
A: 
Step-by-step explanation:
Acceleration is second derivative of position, velocity is first derivative. Therefore, the velocity is the integral of acceleration.

Integrate:

V(0)=-5:

Therefore, v(t):

A general equation to use for this situation is y = mx + b.
For this question, we can assume that y is total cost, m is cost per balloon, x is the amount of balloons, and b as the service fee; so we can set the equation up:
y = (4.50)x + 12
And we can further plug in the total cost to find the number of balloons purchased for the party:
79.50 = (4.50)x + 12
Now we can solve for x (number of balloons):
67.50 = (4.50)x
x = 15
The total number of balloons purchased for the party is 15.
Answer:
8 X 10^(9)
Step-by-step explanation:
Originally we have 10 digit phone numbers excluding the area code.
For each face value we have these in store: 0,1,2,3,4,5,6,7,8,9 (total 10)
But if we exclude 1 and 0 for the first digit, we are left with 8 digits.
8P1 X .......
In a phone number, digits can repeat so we can choose out of these 10 numbers freely after this.
8P1 X 10P1 X 10P1 X...
Adding the area code while assuming 10P1 is just 10...we get:
1 X 1 X 1 X 8 X 10^(9)
= 8000000000
Very interesting question, thanks for the opportunity!