Answer:
x = 10 or x = 2
Step-by-step explanation:
Solve for x:
x^2 - 12 x + 20 = 0
Hint: | Solve the quadratic equation by completing the square.
Subtract 20 from both sides:
x^2 - 12 x = -20
Hint: | Take one half of the coefficient of x and square it, then add it to both sides.
Add 36 to both sides:
x^2 - 12 x + 36 = 16
Hint: | Factor the left hand side.
Write the left hand side as a square:
(x - 6)^2 = 16
Hint: | Eliminate the exponent on the left hand side.
Take the square root of both sides:
x - 6 = 4 or x - 6 = -4
Hint: | Look at the first equation: Solve for x.
Add 6 to both sides:
x = 10 or x - 6 = -4
Hint: | Look at the second equation: Solve for x.
Add 6 to both sides:
Answer: x = 10 or x = 2
So to solve for x, you'll need to combine all the angles and equal it to 720, and from there we can solve.

Combine like terms to get

Subtract 470 on each side to get

Then just divide on each side and you'll get

To find the value of the (x+10) angle, just substitute 125 for x and solve.
The answer is c. 10y and -9y
3.75.....rounded to the nearest dollar would be 4.00