Grilling fish on the fire takes 3 minutes for each side. Both sides of the fish must be grilled. Only two fish can be grilled on the fire at the same time. Now you need to grill 5 fish, at least how much is needed.
在火上烤鱼，每烤一面需要3分钟，鱼两面都要烤，火上只能同时烤两条鱼，现在需要烤5条鱼，至少需要多少．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

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

<gadget id="calculator">6 + 9</gadget>
<output>15</output>

<result>15</result>