15 i really hope this helps
Answer:

Step-by-step explanation:
Given that, a <em>regular octagon </em>is to be constructed.
To find:
Each angle in the octagon = ?
Solution:
We know that a regular triangle (polygon with 3 sides) has an interior angle of
.
And a regular quadrilateral (square) has an interior angle of
.
Therefore, formula for interior angle of a regular polygon with
number of sides can be given as:

For an octagon, we have
.
Value of Interior angle in a regular octagon:

Kindly refer to the attached image for the angle of 
12x=-48 (divide 12 from both sides)
x=-4
10y-13y=30
-3y=30 (divide -3 from both sides)
-10=y
10x+14x=48
24x=48 (divide 24 from both sides)
x=2
Answer:
$10,544.60
Average annual value lost: $6,146.80
First year depreciation: $2,400.00
Total depreciation: $9,445.36
Total depreciation percentage: 47.23%
Value of vehicle at end of ownership period: $10,554.60