The sixth grade students learned from the market survey that the price of crucian carp this month has increased by 15% compared with last month. The price of crucian carp this month is 6.9 yuan per kilogram. How much was the price per kilogram last month?
六年级学生在市场调查中了解到，本月鲫鱼售价比上月提高15%．本月鲫鱼售价为每千克6.9元，上月每千克售价是多少元？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">6.9 / (23/20)</gadget>
<output>6</output>

<result>6</result>