Jane started baby-sitting when she was 18 years old. Whenever she baby-sat for a child, that child was no more than half her age at the time. Jane is currently 34 years old, and she stopped baby-sitting 10 years ago. What is the current age of the oldest person for whom Jane could have baby-sat?
Choose the correct option:  A) 20  B) 21  C) 22  D) 23  E) 25
Check two extreme cases:   Jane = 18, child = 9, years ago = 34-18= 
<gadget id="calculator">34-18</gadget>
<output>16</output>
16 --&gt; child's age now= 9+16= 
<gadget id="calculator">9+16</gadget>
<output>25</output>
25;   Jane= 24, child = 12, years ago = 34-24= 
<gadget id="calculator">34-24</gadget>
<output>10</output>
10 --&gt; child's age now= 12+10= 
<gadget id="calculator">12+10</gadget>
<output>22</output>
22.   Answer: 25.
<result>E</result>
Jane started baby-sitting when she was 18 years old. Whenever she baby-sat for a child, that child was no more than half her age at the time. Jane is currently 34 years old, and she stopped baby-sitting 10 years ago. What is the current age of the oldest person for whom Jane could have baby-sat?