### 9 Answers

- Pramod KumarLv 71 month agoFavourite answer
Angle CBF = 81° = Vertically opposite angle ABD

Since PQ and CD are parallel to each other,

Angles QAB and ABD are co-interior angles. Hence --

QAB + ABD = 180°

=> (5 x + 9) + 81° = 180°

=> 5 x + 90° = 180°

=> 5 x = 90°

=> x = 18 ....................................... Answer

- DavidLv 71 month ago
The value of x = 18 degrees because alternate angles are equal and there are 180 degrees on a straight line

- 1 month ago
(5x+9)+y=180 (Angle on a straight line)

but y=81 (supplementary angles are equal) Thus (5x+9) + 81 = 180. Remove brackets: 5x + 9 + 81 = 180. Collecting like terms, 5x=180-9-81. Thus, 5x=180-90. 5x=90. x=90/5. x=18

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- 1 month ago
(5x + 9) + 81 = 180

5x + 90 = 180

5x = 90

x = 18Thus, the value of x would be equal to 18 degrees.

- rotchmLv 71 month ago
Therefore, the obtuse angle to the right of the 81 is (180 - 81) = 99. [why?].

Now, this 99 is the same figure, same angle as the 5x+9. [why?]

Thus, 99 = 5x+9.

Just solve for x. You know how to do that?

Done!

Hopefully no one will spoil you the answer thereby depriving you from your personal enhancement; that would be very inconsiderate of them.