The sum of (3/10) and (1/5) is equal to (4/5) of a number, what is this number? How many.
(3/10)与(1/5)的和等于一个数的(4/5)，这个数是多少？多少．
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/10) + (1/5)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/2) / (4/5)</gadget>
<output>5/8 = around 0.625</output>

<result>5/8 = around 0.625</result>