The sum of the ages of Zhang Jun, Liu Lin and Ma Ping this year is 38 years old. Four years later, Zhang Jun was 15 years old. How old were Liu Lin and Ma Ping at that time?
今年张军、刘林、马平的年龄和是38岁．四年后张军15岁，那时刘林、马平的年龄和是多少岁．
<gadget id="calculator">15 - 4</gadget>
<output>11</output>

<gadget id="calculator">38 - 11</gadget>
<output>27</output>

<gadget id="calculator">27 + 4 + 4</gadget>
<output>35</output>

<result>35</result>