The sum of two numbers is (4/7), one of the addends is (1/7), what is the other addend?
两个数的和是(4/7)，其中一个加数是(1/7)，另一个加数是多少？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

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

<gadget id="calculator">(4/7) - (1/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>