Multiply Mr. Wang's current age by 2, then subtract 15, and then multiply by 2. It is 90. Do you know how old Mr. Wang is this year? (column equation solution)
王老师现在的年龄先乘2，再减去15，然后再乘2，是90，你知道王老师今年多少岁吗？(列方程解答)
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">30 + 90</gadget>
<output>120</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">120 / 4</gadget>
<output>30</output>

<result>30</result>