Answer:
The value of x is 7 .
Explanation:
By using the property of rhombus .
The diagonals of the rhombus intersect each other at 90° .
Thus
Apply angle sum property of a triangle .
∠(8x + 7) °+ ∠(3x + 6)° +∠ 90 ° = ∠180 °
Open the bracket
8x + 7 + 3x + 6 + 90 = 180
11x + 13 = 180 - 90
11x + 13 = 90
11x = 90 - 13
11x = 77

x = 7
Therefore the value of x is 7 .