I have eight coupons that are all worth -.25
Answer:

Step-by-step explanation:
Because vertical angles are always equal, we want to solve
.
We can add 10 to both sides to get
.
We can subtract
from both sides to get
.
Lastly, we divide both sides by 20 to get
.
So,
and we're done!
The check is left as an exercise to the reader.
Would use the algorithm for solving square root.
For square root, √n
x₁ = 0.5(x₀ + n/x₀)
(This formula is known and for square root, and can be derived using Newton-Raphson's approximation equation)
Where x₀ is the initial guess. x₁ becomes the new guess.
For √100.6 let our initial guess be 10, x₀ = 10, n = 100.6
Our approximation shall be to 3 decimal places. Once we get the same answer twice we stop the algorithm.
x₀ = 10, x₁ = 0.5(x₀ + n/x₀), x₁ = 0.5(10 + 100.6/10) = 10.030, x₁ = 10.030
x₂ = 0.5(x₁ + n/x₁), x = 0.5(10.030 + 100.6/10.030) ≈10.015, x₂ ≈ 10.030 (to 3 decimal places)
Since x₂≈ x₁, the algorithm stops.
So the √100.6 is ≈ 10.030 to 3 decimal places.
I hope this helps.
Answer: 
Step-by-step explanation:
You know that the formula to find the sum of a finite geometric series is:

Where
is the number of terms,
is the first term and
is the common ratio (
).
The steps to find the sum of the first 12 terms of the given geometric serie, are:
1. Find the common ratio "r". By definition:

Then:

2. Finally, knowing that:

You must substitute values into the formula.
Then you get:
