∠1, ∠2, ∠3 are the three interior angles of a right triangle. Knowing that ∠1 is a right angle, ∠2=30°, then ∠3=how many degrees.
∠1、∠2、∠3是一个直角三角形的三内角，已知∠1是直角，∠2=30°，则∠3=多少°．
<gadget id="calculator">90 - 30</gadget>
<output>60</output>

<gadget id="calculator">180 - 60</gadget>
<output>120</output>

<gadget id="calculator">180 - 120</gadget>
<output>60</output>

<result>60</result>