Q:

In the class of boys and girls, the rank of Obama is15th and the rank of Shabana is 8th.The rank of Obama is 8th only in boys and Shabana’s rank is 4th only in girls. In the boys and girls, Obama’s rank is 18th from other side. Shabana’s rank is 7th only in girls from other end. Then find the total number of boys in the class. 

• 1
  18
• 2
  21
• 3
  15
• 4
  11