Answer:
Law of Sines
Step-by-step explanation:
Law of Sines: 
Step 1: Solve for m∠B

25sinx = 27sin36°
sinx = 27sin36°/25

m∠B ≈ 39.4°
Step 3: Find m∠C
180 - (36 + 39.4)
180 - 75.4
m∠C = 104.6°
<span>circumference = 2 π r
138.16 = 2 π r
138.16/2π = 2π/2π r
21.98884694 =r
D</span><span>iameter = r X 2
</span>Diameter = <span><span>21.98884694</span> X 2</span>
Diameter = 43.97769388
Take the second equation and flip it around so the y on the left ends up on the right and the 4x on the right ends up on the left. This makes all negatives positive and all positives negative. -4x + 12 = y
Then add the first equation to the second equation
4x +12 = -7y
<u>-4x + 12 </u>=<u> y </u> this eliminates the x's
<u>24</u> = -<u> 6y</u> then divide by - 6
- 6 - 6
- 4 = y<u>
</u>So if you know that y = negative 4, you can substitute into either equation. I pick the second one because I am a lazy person.
-y + 12 = 4 x
-(-4) + 12 = 4 x combine your numbers<u>
</u> <u> 16 </u> = <u>4 x </u> then divide by 4<u>
</u> 4 = x
So your solution is: x = 4 and y = -4 or this is also written (4, -4)
Does that work for you?
.7 repeating would make it 7/9