Xiao Ming said that this year his age is 3 years younger than his grandfather's 30%. It is known that Xiao Ming is 15 years old this year, how old is grandpa? (Solution of column equation)
小明说，今年他的年龄比爷爷的30%还小3岁．已知小明今年15岁，爷爷今年多少岁？(列方程解)
<gadget id="calculator">3 - 3</gadget>
<output>0</output>

<gadget id="calculator">3 + 15 + 0</gadget>
<output>18</output>

<gadget id="calculator">18 / 0.3</gadget>
<output>60</output>

<result>60</result>