[tex]\boxed{\pink{\sf\leadsto Value \ of \ x \ is \ 24^{\circ}}}[/tex]
In the given parallelogram we can see that , <B is 5x° and <C is equal to 2x + 12°.
And these two are co - interior angles . And sum of co - interior angles is 180°.
Hence , here
[tex]\tt:\implies \angle DCB + \angle ABC = 180^{\circ} \\\\\tt:\implies (2x + 12)^{\circ} + 5x^{\circ}=180^{\circ} \\\\\tt:\implies 7x = (180 - 12 )^{\circ} \\\\\tt:\implies 7x = 168^{\circ} \\\\\tt:\implies x =\dfrac{168^{\circ}}{7} \\\\\underline{\boxed{\red{\tt\longmapsto x = 24^{\circ}}}}[/tex]
[tex]\rule{200}2[/tex]