Answer:
m∠CBD=68°
Explanation:
BA is perpendicular to BD, meaning they form a right angle (90°)
This means m∠CBD + m∠ABC=90, or they are supplementary.
We have expressions given for these angles, so
4x+52+8x-10=90
12x+42=90
12x=48
x=4
Knowing x=4, we can substitute back into our expression for m∠CBD because that's what we're looking for.
4(4)+52=68
m∠CBD is 68°.