Nakir and Sabir is twin brother. Their combined age now is equal to their father's age. After 10 years
The combined age of Nakir and Sabir is still equal to their father's age.
Their father's age is three times higher than Sabir's age.
The combined age of Nakir and Sabir is higher than their father's age.
The combined age of twins is less than their father's age.