When Rahul was born, his father was 30 years older than his brother and his mother was 24 years older than his sister. If Rahul's brother is 6 years older than him and his mother is 3 years younger than his father, how old was Rahul's sister when he was born ?  Choose the correct choice from the following answers.
A) 10 years
B) 7 years
C) 8 years
D) 9 years
E) 12 years
When Rahul was born, his brother's age = 6 years; his father's age = (6 + 30)= 
<gadget id="calculator">(6 + 30)</gadget>
<output>36</output>
36 years,   his mother's age= (36 - 3)= 
<gadget id="calculator">(36 - 3)</gadget>
<output>33</output>
33 years;   his sister's age= (33 - 24)= 
<gadget id="calculator">(33 - 24)</gadget>
<output>9</output>
9 years.   Answer: Option 9 years
<result>D</result>
When Rahul was born, his father was 30 years older than his brother and his mother was 24 years older than his sister. If Rahul's brother is 6 years older than him and his mother is 3 years younger than his father, how old was Rahul's sister when he was born ?