Respuesta :

Given that AC= AD and AB is a perpendicular bisector of CD, 

7x + 3 = 5x + 9
2x = 6
x = 3

∠CAD = 7x + 3 + 5x + 9 = 7(3) + 3 + 5(3) + 9 = 48°

m∠C  = (180 - 48) ÷ 2 = 66°     | Isosceles Δ 

Answer: 66° (Answer C)