3 years ago, father's age was 8 times of Mingming's age, and this year, father's age is 5 times of Mingming's age, so how old is father this year?
3年前，爸爸的年龄是明明年龄的8倍，在今年，爸爸的年龄是明明年龄的5倍，则爸爸今年多少岁．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">8 / 7</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">(5/4) - (8/7)</gadget>
<output>3/28 = around 0.107143</output>

<gadget id="calculator">3 / (3/28)</gadget>
<output>28</output>

<gadget id="calculator">28 * (5/4)</gadget>
<output>35</output>

<result>35</result>