Subtract 30 from a certain number, multiply by 3, and finally subtract 300. The result is 60. What is this number?
某数减去30，再乘3，最后减去300，结果等于60，这个数是多少？
<gadget id="calculator">60 + 300</gadget>
<output>360</output>

<gadget id="calculator">360 / 3</gadget>
<output>120</output>

<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<result>150</result>