Add (2/5) to (3/4) of a number, and the sum is (5/8). What is this number?
一个数的(3/4)加上(2/5)，和是(5/8)．这个数是多少？
<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(5/8) - (2/5)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(9/40) / (3/4)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>