73. Put 235 matches into three boxes, so that $\frac{3}{4}$ of the matches in the first box equals $\frac{1}{3}$ of the matches in the second box, and $\frac{1}{2}$ of the matches in the second box equals $\frac{3}{7}$ of the matches in the third box, then the second box has $\qquad$ matches?
Reference answer: 90