In the oral calculation competition held in the fifth grade, Zhang Yan did 150 questions, which was 30 questions less than twice what Wang Gang did. How many questions did Wang Gang do? (solution by equation)
在五年级举办的口算比赛中，张燕做了150道题，比王刚做的2倍少30道．王刚做了多少道题？(用方程解)
<gadget id="calculator">150 + 30</gadget>
<output>180</output>

<gadget id="calculator">180 / 2</gadget>
<output>90</output>

<result>90</result>