In order to encourage residents to save water, the water supply company stipulates that when the water used by each person does not exceed 2 cubic meters per month, the fee is 0.5 yuan per cubic meter; the part that exceeds 2 cubic meters is charged at 5 yuan per cubic meter. There are 3 members of Wang Hong’s family, and they paid a total of 13 yuan for water last month. Please calculate how many cubic meters of water Wang Hong’s family used last month?
自来水公司为鼓励居民节约用水，规定每人每月用水不超过2立方米时，按每立方米0.5元收费；超过2立方米的部分按每立方米5元收费．王红家3口人，上月共交水费13元，请你算一算王红家上月用水多少立方米？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">3 * 2 * 0.5</gadget>
<output>3</output>

<gadget id="calculator">13 - 3</gadget>
<output>10</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">6 + 2</gadget>
<output>8</output>

<result>8</result>