In the ratio, the two inner terms are (3/7) and (7/15), then what is the product of the two outer terms.
在比例中，两个内项分别是(3/7)和(7/15)，那么两个外项的积是多少．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

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

<gadget id="calculator">(3/7) * (7/15)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>