The electricity bill of Pingping's family was 171 yuan last month, which was three times the water bill of her family last month. How much was her water bill last month?
平平家上个月电费为171元，相当于她家上个月水费的3倍．她家上个月水费多少元？
<gadget id="calculator">171 / 3</gadget>
<output>57</output>

<result>57</result>