Mom bought some candy for Mingming and Lingling's grandma, 8 pieces, and the rest for Mingming and Lingling. Mom gave Mingming half of the existing candy, and gave Lingling the remaining half of the candy. At this time, mother still had 3 candies in her hand. How many candies did my mother buy in total?
妈妈买了一些糖给明明和玲玲的奶奶8粒，余下的给明明和玲玲吃．妈妈给了明明现有糖的一半，再给玲玲剩下糖的一半，这时妈妈手里还有3颗糖．妈妈一共买了多少颗糖．
<gadget id="calculator">3 * 2 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<result>20</result>