In a right triangle, the ratio of one acute angle to the right angle is 2:3, what is the degree of the other acute angle.
一个直角三角形，一个锐角与直角的比是2：3，另一个锐角是多少度．
<gadget id="calculator">90 / 3</gadget>
<output>30</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">180 - 90 - 60</gadget>
<output>30</output>

<result>30</result>