Mark is 18 years old. He has a little brother, John, who is 10 years younger. If John and Mark's parents are currently 5 times older than John, how old were they when Mark was born?
John is 8 years old because 18-10=
<gadget id="calculator">18-10</gadget>
<output>8</output>
8 years old.
Their parents are currently 40 years old because 8*5=
<gadget id="calculator">8*5</gadget>
<output>40</output>
40.
Therefore, they were 22 when Mark was born because 40-18 = 
<gadget id="calculator">40-18</gadget>
<output>22</output>
22 years old.

<result>22</result>