The age of the grandfather and the grandson is less than 90 years old this year, and the age of the grandfather is 7 times that of the grandson; after a few years, the age of the grandfather is 6 times that of the grandson; after a few years, the age of the grandfather is 5 times that of the grandson. So, how old was grandpa in 1949?
爷爷和孙子今年的年龄和不足90岁，爷爷的年龄是孙子的7倍；若干年后，爷爷的年龄是孙子的6倍；再过若干年后，爷爷的年龄是孙子的5倍．那么，1949年爷爷是多少岁．
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">60 / 6</gadget>
<output>10</output>

<gadget id="calculator">10 * 7</gadget>
<output>70</output>

<gadget id="calculator">2_014 - 1_949</gadget>
<output>65</output>

<gadget id="calculator">70 - 65</gadget>
<output>5</output>

<result>5</result>