Hey mattjp213.

Hint: Break up the cases (you will have four cases) for ||x-5|-10|. The first case is 5-x when x < 5 and x-5 when x >= 5. Now you have |5-x-10| and |x-5-10| and you need to figure out when this expresion is < 0 and >= 0 which will be related to when |-x-5| and |x-15| are whatever they are.