Given that
The two sides of the triangle are 6x and 3x+9 and the two angles are 65 degrees each.
Explanation -
According to the property of the triangle " If the two angles of the triangle are equal then the sides opposite to them will be equal."
Then, we have
AB = BC -------------because angle A = angle B = 65
Substituting their values
6x = 3x + 9
6x - 3x = 9
3x = 9
x = 9/3 = 3
x = 3
So side AB will be,
AB = 6(3) = 18 units.
So opption D is correct.
Hence the final answer is 18.