Subtract the difference between (7/15) and (7/30) from a number, and the result is (2/3). What is this number?
一个数减去(7/15)与(7/30)的差，结果是(2/3)，这个数是多少？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">7 / 15</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">7 / 30</gadget>
<output>7/30 = around 0.233333</output>

<gadget id="calculator">(7/15) - (7/30)</gadget>
<output>7/30 = around 0.233333</output>

<gadget id="calculator">(2/3) + (7/30)</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>