Xiao Gang and Xiao Ming each have a certain number of glass beads. Now Xiao Gang has 21 more glass beads than Xiao Ming. If Xiao Gang gives Xiao Ming a few glass beads, Xiao Ming has 5 more glass beads than Xiao Gang, then How many glass beads did Xiao Gang give Xiao Ming?
小刚和小明各有一定数量的玻璃珠，现在小刚比小明多出21个玻璃珠，如果小刚送给小明几个玻璃珠后，小明的玻璃珠反而比小刚多出5个，那么小刚到底送给小明多少个玻璃珠．
<gadget id="calculator">21 + 5</gadget>
<output>26</output>

<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<result>13</result>