It costs 510 yuan to buy 6 pieces of the same short-sleeved shirt. If you use this money to buy a long-sleeved shirt, you need to buy 2 less. How much is the unit price of long-sleeved shirts?
买6件同样的短袖衬衫要用510元，如果用这些钱买长袖衬衫，就要少买2件．长袖衬衫的单价是多少元/件？
<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">510 / 4</gadget>
<output>255/2 = around 127.5</output>

<result>255/2 = around 127.5</result>