<s>[INST] For the reaction [M]\(\rightarrow\)[M\({}^{\prime}\)], where [M] represents a compound of molecular weight 135 and [M\({}^{\prime}\)] represents a new compound due to loss of a neutral fragment, the mass spectrum shows metastable peaks for the transition at \(m/z\) 91 and \(m/z\) 117. What is the mass of the neutral fragment?[/INST]