Algebra: find the value of each variable

Hey, I'm not too quite sure about my answers, but I figured I'd give it a shot.

Let me show you what I did to get my answers.

1. Those little ticks on the triangles means that they're equal. A triangle has a sum of 180 so I took:

2x+2x+40=180

4x+40=180

4x=140

x=35

2. The curves on the sides means that they're also equal so I did:

2x+6=3x-6

2x=3x-12

-x=-12

x=12

4. This is similar to #1. Keep in mind that a right angle has a degree of 90.

5x+5x+90=180

10x+90=180

10x=90

x=9

5. Repeat.

6x+6+6x+6+2x=180

14x+12=180

14x=168

x=12

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this

my answer is$ 12

step-by-step explanation:

because 15 -2=12