A, B, and C buy watermelons with the same amount of money. When dividing watermelons, both A and C take 7.5 kg more watermelons than B. As a result, A and C each give B 1.5 yuan. How much is a kilogram of watermelon?
甲、乙、丙三人用同样多的钱合买西瓜．分西瓜时，甲和丙都比乙多拿西瓜7.5千克．结果甲和丙各给乙1.5元钱．每千克西瓜多少元？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">7.5 * (2/3)</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1.5 * (2/5)</gadget>
<output>0.6</output>

<result>0.6</result>