Consider the expression 
This expression contains two terms with 
group them:
Now simplify term 
Now 
This expression is defined for all x.
Since this is a triangle all the angles within the triangle add up to 180 degrees so....
82+(9x+2)+(7x)=180
82+2+16x=180
16x+84=180
16x=96
X=6
If we plug in X to angle(9x+2) and angle (7x) we will get 56 and 42. We can get angle 2 by subtracting 180-42 which is 138
FINAL ANSWER: 138 degrees
Half of the distance from one side, through the middle, to the other side.
circumference: 3.14*radius*2
24
x
^2
+
54
x
+
21,
if you would like me to explain how to do it, I can in the comments.
One month = 5000
Number of months before the spark plugs need to change :
15000 ÷ 5000 = 3
The sparks can last 3 months before it needs to be changed.
Number of times it need to change in a year = 12 ÷ 3 = 4
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Answer : It needs to be change 4 times a year.
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