Two sisters are shopping. The older sister brings twice as much money as the younger sister. The elder sister spends 180 yuan and the younger sister spends 30 yuan. At this time, the remaining money of the two is equal. Ask the older sister how much money she brought.
姐妹两人买东西，姐姐带的钱数是妹妹的2倍，姐姐用去180元，妹妹用去30元，这时二人剩下的钱数相等，问姐姐原来带多少元．
<gadget id="calculator">180 - 30</gadget>
<output>150</output>

<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">150 / 1</gadget>
<output>150</output>

<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<result>300</result>