The grandfather said: "Add 12 to my age, divide by 4, then subtract 15, and multiply by 10, which is exactly 100 years old." How old is this old man now?
老爷爷说："把我的年龄加上12，再用4除，然后减去15，再乘以10，恰好是100岁．"这位老爷爷现在有多少岁．
<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 - 12</gadget>
<output>88</output>

<result>88</result>