Three years ago the average age of a family of seven members was 20 years. A boy have been born, the average age of the family is the same today. What is the age of the boy? Pick:
A) A)8 B) B)7 C) C)6 D) D)5 E) E)4
7 * 23= 
<gadget id="calculator">7 * 23</gadget>
<output>161</output>
161   7 * 19= 153   --------------   8   8nswer: 8
<result>A</result>
Three years ago the average age of a family of seven members was 20 years. A boy have been born, the average age of the family is the same today. What is the age of the boy?