The quotient of dividing 45 by (9/7) is 15 more than a number. Find this number (use the equation to solve it).
45除以(9/7)的商比一个数多15，求这个数(用方程解)．
<gadget id="calculator">9 / 7</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">15 * (9/7)</gadget>
<output>135/7 = around 19.285714</output>

<gadget id="calculator">45 - (135/7)</gadget>
<output>180/7 = around 25.714286</output>

<gadget id="calculator">(180/7) / (9/7)</gadget>
<output>20</output>

<result>20</result>