Hello! Remember you have to write complete questions in order to get good and exact answers. Here we have no expressions for ∠CBD and ∠ABC, so I'll assume:
[tex]\angle CBD=15x-24 \\ \\ \angle ABC=20x+40[/tex]
We know that the measure of ∠CBD is 45% of the measure of ∠ABC, then:
[tex]\angle CBD = 45\%(\angle ABC) \\ \\ \\ Or: \\ \\ \angle CBD = 0.45(\angle ABC) \\ \\ \\ Substituting \ expressions: \\ \\ 15x-24=0.45(20x+40) \\ \\ \\ Solving \ for \ x: \\ \\ 15x-24=9x+18 \\ \\ 15x-9x=24+18 \\ \\ 6x=42 \\ \\ x=\frac{42}{6} \\ \\ \boxed{x=7}[/tex]
