The sum of a number and (1/7) is equal to 45% of (4/9). What is this number?
一个数与(1/7)的和等于(4/9)的45%，这个数是多少？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(4/9) * (9/20)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/5) - (1/7)</gadget>
<output>2/35 = around 0.057143</output>

<result>2/35 = around 0.057143</result>