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 12 years ago. What is the current age of the oldest person for whom Jane could have baby-sat? Pick:
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= 22, child = 11, years ago = 34-22= 
<gadget id="calculator">34-22</gadget>
<output>12</output>
12 --&gt; child's age now= 11+12= 
<gadget id="calculator">11+12</gadget>
<output>23</output>
23.   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 12 years ago. What is the current age of the oldest person for whom Jane could have baby-sat?