Answers:
x = 12
angle A = 30 degrees
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Step-by-step explanation:
Check out the attached image below.
Note the pair of (8x+4) angles which are congruent vertical angles.
Also, notice that 50+130 = 180 since those adjacent angles are supplementary. In other words, they form a straight line.
Now that we know the expressions for each interior angle, we add them up and set the sum equal to 180. Recall that for any triangle, the interior angles always add to 180.
Let's solve for x
(3x-6) + (8x+4) + (50) = 180
11x + 48 = 180 .... combine like terms
11x = 180-48 ..... subtract 48 from both sides
11x = 132
x = 132/11 ..... divide both sides by 11
x = 12
Use this to find the value of angle A
A = 3x-6
A = 3*12-6
A = 36 - 6
A = 30
For the sake of completeness, let's find 8x+4 as well. This part is optional
8x+4 = 8*12+4 = 96+4 = 100
The three interior angles of the triangle are: 30, 100, 50
Note how 30+100+50 = 180 to help confirm the answer.