32 students are playing singles or doubles in front of 10 table tennis tables (1 table for singles with 2 players, doubles with 1 table for 4 players). How many ping pong tables are there for a doubles match?
32个同学正在10张乒乓球桌前进行单打或双打比赛(单打1张球桌2人，双打1张球桌4人)．正在进行双打比赛的乒乓球桌有几张？
<gadget id="calculator">32 - 20</gadget>
<output>12</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>