If the value of \(\displaystyle \frac{3\cos 36^\circ + 5\sin 18^\circ}{5\cos 36^\circ - 3\sin 18^\circ} \) is \(\displaystyle \frac{a\sqrt{5} - b}{c} \), where \( a \), \( b \), \( c \) are natural numbers and \( \gcd(a,c)=1 \), then \( a+b+c \) is equal to :
