In a right triangle, the ratio of the largest angle to the number of one acute angle is 5:4, what is the degree of the other acute angle.
一个直角三角形中，最大角和一个锐角度数之比为5：4，另一个锐角是多少度．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">90 * (4/5)</gadget>
<output>72</output>

<gadget id="calculator">180 - 90 - 72</gadget>
<output>18</output>

<result>18</result>