Question

In the given figure, find the value of x.
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Answer 1

Step-by-step explanation:

the answer is in above picture

according to exterior angle theroem

angle A + angle C = angle ABD

5x-4 + 4x -11 = 129

9x -15 = 129

9x = 144

x = 16

or

let angle ABC = y

y + 5x -4 + 4x -11 = 180°

(sum of all angles of triangle is 180°)

9x -15 +y = 180

9x + y = 195

then

angle ABD + angle ABC = 180

(LINEAR PAIR)

129 + y = 180

y = 51

put value of y in first equation

9x + y = 195

y = 51

9x + 51 = 195

9x = 144

x = 144/9

x = 16