Answer:
2y+6x=180
Explanation:
Because we know that side lengths BD, DC, and AD are all congruent, we can conclude that triangles BDA and CDA are congruent because they have at least two congruent sides. Since these triangles are both 45-45-90 triangles, angle C is equal to 45 degrees, or 3x. 45/3 is 15, so x=15. Angle B is equal to 45 degrees, or y, so y=45.
From there, we plug these numbers into the equation with 2(45) + 6(15), or 90+90 = 180.