This year, A is 20 years old, B is 18 years old, C is 12 years old, and Ding is 8 years old. How many years later, the sum of the ages of A, B, and C is equal to 5 times the age of Ding.
今年甲20岁，乙18岁，丙12岁，丁8岁，多少年后，甲、乙、丙的年龄和等于丁的年龄的5倍．
<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">12 - 40</gadget>
<output>-28</output>

<gadget id="calculator">20 + 18 + (-28)</gadget>
<output>10</output>

<gadget id="calculator">5 - 1 - 1 - 1</gadget>
<output>2</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<result>5</result>