Xiao Ming is 12 years old this year, and his grandfather will be four times as old as Xiao Ming in 6 years. How old is grandpa this year?
小明今年12岁，6年后爷爷的年龄是小明的4倍，爷爷今年多少岁？
<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">18 * 4</gadget>
<output>72</output>

<gadget id="calculator">72 - 6</gadget>
<output>66</output>

<result>66</result>