There are three numbers A, B, and C. It is known that A is larger than B (2/5), and B is larger than C (1/7), so how much is A larger than C?
三个数A，B，C，已知A比B大(2/5)，B比C大(1/7)，则A比C大几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) + (1/7)</gadget>
<output>19/35 = around 0.542857</output>

<result>19/35 = around 0.542857</result>