Answer:
x=5
Step-by-step explanation:
First, let's understand logarithms.
When there is no base given, like in this problem's right side of the equation, the base is automatically 10.
So, let's re-write that.

Now, let's test a few of the numbers out. For brevity, I already know it's 3. Let's show you why.

Answer:
The answer in this problem would be A
If this exact question is repeatedly deleted, it's probably because of the ambiguity of the given equation. I see two likely interpretations, for instance:

or

If the first one is what you intended, then

and it follows that
2<em>k</em> + 8 = 3 ==> 2<em>k</em> = -5 ==> <em>k</em> = -5/2
If you meant the second one, then

which would give
<em>k</em> + 9 = 3 ==> <em>k</em> = -6
And for all I know, you might have meant some other alternative... When you can, you should include a picture of your problem.
The formula for the circumference is 2πr.
The diameter d is given, which is 2 times the radius r (d = 2r)
So you have to calculate π d = 3.142×1.8 ≈ 5.7