The correct answer is: [C]: " 36° " .
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Step-by-step explanation:
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We are asked to find the value for "x" .
Note: From the diagram provided, we can see that there are TWO (2) angles with the given measurements: "4x" ; and "x" .
Note that these TWO (2) angles both completely form a "straight line".
As such, these TWO (2) angles are "supplementary angles" (by definition).
Furthermore, and by definition, all supplementary angles add up to 180° .
Thus:
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→ "4x" + "x" = 4x + x = 180 ;
→ 5x = 180 ; Solve for "x" ;
→ Divide EACH SIDE of the equation by "5" ;
to isolate "x" on one side of the equation; & to solve for "x" ;
→ 5x / 5 = 180 / 5 ;
→ to get:
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→ x = 36 .
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→ which is: "Answer choice: [C]: " 36° " .
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