After subtracting 15 from the age of Xiao Ming’s grandfather this year, it will be reduced by 4 times, and after subtracting 6, it will be enlarged by 10 times, which is exactly 100. How old is Xiao Ming's grandfather this year?
小明的爷爷今年的年纪减去15后，缩小4倍，再减去6之后，扩大10倍，恰好是100．小明的爷爷今年多少岁．
<gadget id="calculator">100 / 10</gadget>
<output>10</output>

<gadget id="calculator">10 + 6</gadget>
<output>16</output>

<gadget id="calculator">16 * 4</gadget>
<output>64</output>

<gadget id="calculator">64 + 15</gadget>
<output>79</output>

<result>79</result>