Zhang Ming is 13 years old this year, and his grandfather is 8 years younger than six times his age. How old is his grandfather this year?
张明今年13岁，爷爷的年龄比他的6倍少8岁，爷爷今年多少岁？
<gadget id="calculator">13 * 6</gadget>
<output>78</output>

<gadget id="calculator">78 - 8</gadget>
<output>70</output>

<result>70</result>