After adding 17 to grandpa's age this year, it will be reduced by 4 times, and after subtracting 15, it will be enlarged by 10 times, which is exactly 100 years old. How old is grandpa this year?
明明爷爷今年的年龄加上17后，再缩小4倍，再减去15后，扩大10倍，恰好是100岁，明明爷爷今年多少岁．
<gadget id="calculator">100 / 10</gadget>
<output>10</output>

<gadget id="calculator">10 + 15</gadget>
<output>25</output>

<gadget id="calculator">25 * 4</gadget>
<output>100</output>

<gadget id="calculator">100 - 17</gadget>
<output>83</output>

<result>83</result>