Three years ago the average age of a class of six members was 20 years. A boy have been added, the average age of the class is the same today. What is the age of the boy? Choose the correct choice from the following: A) A)1 B) B)2 C) C)3 D) D)4 E) E)5
6 * 23= 
<gadget id="calculator">6 * 23</gadget>
<output>138</output>
138   7 * 20= 
<gadget id="calculator">7 * 20</gadget>
<output>140</output>
140   `2   2
<result>B</result>
Three years ago the average age of a class of six members was 20 years. A boy have been added, the average age of the class is the same today. What is the age of the boy?