One x, two x, three x

Geometry Level 3

If $\sin {x} = -13\cos{x}$ . Then, the value of

$\begin{aligned} \frac{\sin {x} + \sin{2x} + \sin{3x}}{\cos{x}+\cos{2x}+\cos{3x}} \end{aligned}$

can be expressed in the form $\frac{a}{b}$ , where $a$ and $b$ are positive coprime integers. What is the value of $a+b$ ?