9514 1404 393
Answer:
y = 12
Step-by-step explanation:
Triangles ABD and CBD are congruent, so DA = DC:
3y +6 = 5y -18
24 = 2y . . . . . . . . add 18-3y; next, divide by 2
12 = y
_____
Additional comment
In some variations of this question, you may be asked to solve for x. Since the angles are equal, you have ...
3x -1 = 34 -2x ⇒ 5x = 35 ⇒ x = 7 . . . (consistent with ∠ABC = 40°)
