White Tiger Electronics produces $CD$ players using an automated assembly line process. The standard cost of $CD$ players is $$155$ per unit $($labor$,$ $$35$; materials, $$67$; and overhead, $$53).$ The sales price is $$325$ per unit.

a$.$ To achieve a $15$ percent multifactor productivity improvement by reducing materials costs only, one needs to reduce the materials cost by parcent. $($Enter your response as a percent rounded to two decimal places.$)$