UPSC 2014 CDS I Math Paper

Ravi's father was 28 years of age when his sister was born and his sister was 4 years of age when his brother was born.
Therefore, age of Ravi’s father when his brother was born =28+4=32 years
When Ravi was born, his mother's age was 26 years and his elder brother was 3 years older to him.
Therefore, Ravi’s mother's age when his brother was born =26−3=23 years