Wang Gang bought 1 fountain pen and 2 writing brushes, which cost 24 yuan in total. The unit price of 1 pen is exactly equal to the price of 2 writing brushes. How much is 1 writing brush?
王刚买1支钢笔和2支毛笔，一共用去24元．1支钢笔的单价正好等于2支毛笔的价钱1支毛笔多少元？
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">24 / 4</gadget>
<output>6</output>

<result>6</result>