a/b=28...13, and a+b+28+13=924, how much is b= in the formula.
a/b=28…13，且a+b+28+13=924，式子中b=多少．
<gadget id="calculator">924 - 28 - 13</gadget>
<output>883</output>

<gadget id="calculator">883 - 13</gadget>
<output>870</output>

<gadget id="calculator">28 + 1</gadget>
<output>29</output>

<gadget id="calculator">870 / 29</gadget>
<output>30</output>

<result>30</result>