Question 16·Hard·Problem Solving and Data Analysis

A box contains only red and blue pens.

• Exactly 50% of the red pens and $33\frac{1}{3}\%$ (one-third) of the blue pens are removed.
• After the removal, the box contains a total of 68 pens, with an equal number of pens of each color.

How many blue pens were in the box before any pens were removed?