One inner term of the known ratio is 15 more than the other inner term (1/4), and one outer term is 18, what is the other outer term.
已知比例的一个内项是15比另一个内项多(1/4)，一个外项是18，另一个外项是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">15 / (5/4) / 18</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">15 * (2/3)</gadget>
<output>10</output>

<result>10</result>