In 1992, the age of the grandfather was 10 times that of the grandson. After 12 years, the age of the grandfather was 4 times that of the grandson. So how old was the grandson in 1993?
1992年爷爷年龄是孙子的10倍，再过12年，爷爷年龄是孙子子的4倍，那么1993年孙子是多少岁．
<gadget id="calculator">12 * 4</gadget>
<output>48</output>

<gadget id="calculator">48 - 12</gadget>
<output>36</output>

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<gadget id="calculator">36 / 6</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>