The value of x in the diagram is 6
A parallelogram is a quadrilateral with two pairs of parallel lines.
The opposite sides of a parallelogram are equal and the opposite corresponding angles are equal.
The adjascent sides of a parallelogram are supplementary this means they add up to 180°.
With this theorem, it means that ;
6x - 15 = x + 15
collect like terms
6x - x = 15 + 15
5x = 30
divide both sides by 5
x = 30/5
x = 6
Therefore, the value of x in the parallelogram is 6