Answer:
(b) x = 5
Explanation:
You want to know the value of x if the acute and obtuse angles of an isosceles trapezoid are marked 51° and (28x-11)°.
Angle relation
The acute and obtuse angles in an isosceles trapezoid are supplementary, so ...
51° +(28x -11)° = 180°
28x = 140 . . . . . . . . . divide by °, subtract 40
x = 5 . . . . . . . . . . . divide by 28
The value of x is 5.
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Additional comment
None of the other answer choices makes any sense, as the angle cannot be greater than 180°. 28x less than 180° means x < 6.4, so there is only one viable answer choice.
None of the answers with decimal values can work, since multiplying by 28 will result in a number with a decimal fraction. The sum of that and other integers cannot be 180°.
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