Xiao Ming and Xiao Hong took a total of 200 yuan to go shopping, and the amount of money left after the shopping was exactly the same. It is known that the ratio of the amount of money spent by Xiao Ming to his original amount is 3:7, and the ratio of the amount of money spent by Xiao Hong to her original amount is 9:13. How much money did Xiao Ming spend?
小明和小红两人共带200元钱去购物，购完后两人剩下的钱数正好相等．已知小明花去的钱数与他原来的钱数的比是3：7，小红花去的钱数和她原来钱数的比是9：13，小明花去多少钱？
<gadget id="calculator">7 + 13</gadget>
<output>20</output>

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">7 / 3</gadget>
<output>7/3 = around 2.333333</output>

<gadget id="calculator">1 - (7/3)</gadget>
<output>-4/3 = around -1.333333</output>

<gadget id="calculator">13 / 9</gadget>
<output>13/9 = around 1.444444</output>

<gadget id="calculator">1 - (13/9)</gadget>
<output>-4/9 = around -0.444444</output>

<gadget id="calculator">(-4/3) / (-4/9) / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">200 * (7/20) * (3/7)</gadget>
<output>30</output>

<result>30</result>