A single-plank bridge is 5 meters long. The mother goat wants to take 3 lambs across the river to play. If only one lamb can be taken across the bridge at a time, how many meters does the mother goat have to walk in total?
一座独木桥长5米，山羊妈妈想带3只小羊到河对面去玩．如果每次只能带1只小羊过桥，那么山羊妈妈一共要走多少米？
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>