When Grandma Wang bakes pancakes on the street, she can only bake two pancakes at a time, both sides need to be baked, and each side takes 3 minutes. Xiao Ming’s family needs to bake 15 pancakes, how many minutes does Grandma Wang need at least?
王奶奶在大街上烙饼，每次只能烙两张饼，两面都要烙，每面要3分钟，小明家要烙15张饼，王奶奶至少要多少分钟．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">3 * 2 * 6</gadget>
<output>36</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">36 + 9</gadget>
<output>45</output>

<result>45</result>