Reflection of C is on AB

Geometry Level 2

A right angle triangle $ABC$ is such that $AC=24$ cm, $CB=10$ cm and $\angle ACB=90^{\circ}$ . A point $D$ on $CB$ is such that when point $C$ is reflected upon line $AD$ , the reflected point will be on line $AB$ . The length of $CD=\frac{a}{b}$ where $a$ and $b$ are coprime integers. Find the value of $a+b$ .