Coordinate Geometry: JEE Main 2010 Mathematics question

The line $L$ given by ${x \over 5} + {y \over b} = 1$ passes through the point $\left( {13,32} \right)$. The line K is parrallel to $L$ and has the equation ${x \over c} + {y \over 3} = 1.$ Then the distance between $L$ and $K$ is :