If 12+((2/5)*0.75+((1/2)+△)*3)+0.3=98, then △=how much.
若12+((2/5)*0.75+((1/2)+△)*3)+0.3=98，那么△=多少．
<gadget id="calculator">839 / 30</gadget>
<output>839/30 = around 27.966667</output>

<result>839/30 = around 27.966667</result>