How to find missing frequency if the mode of the given data is given.

Just use the formula and solve by putting the values.
Mode =L+ F₁ - F₀/2F₁ - F₀ - F₂ *H
; where F1= frequency of modal class( class interval containing the mode)
               F2=frequency of class succeeding(after) the modal class.
              F0=frequency of class  preceding(before) the modal class.
              L= lower limit of the modal class.
              H = class size.