Virginia, Adrienne, and Dennis have taught history for a combined total of 96 years. If Virginia has taught for 9 more years than Adrienne and for 12 fewer years than Dennis, for how many years has Dennis taught?
Choose the correct option:
A) 23 B) 32 C) 35 D) 41 E) 42
Let number of years taught by Virginia = V   number of years taught by Adrienne = A   number of years taught by Dennis = D   V+A+D = 96   V= A+9   =&gt;A = V-9   V= D-12   =&gt; A = (D-12)-9 = D-21   D-9 + D-21 + D = 96   =&gt; 3D = 96 + 30= 
<gadget id="calculator">96 + 30</gadget>
<output>126</output>
126=&gt; D = 42   Answer 42
<result>E</result>
Virginia, Adrienne, and Dennis have taught history for a combined total of 96 years. If Virginia has taught for 9 more years than Adrienne and for 12 fewer years than Dennis, for how many years has Dennis taught?