Let their ages 6 years ago be 6x and 5x. Present ages are 6x+6 and 5x+6. In 4 years, ages will be 6x+10 and 5x+10. Ratio: (6x+10)/(5x+10)=11/10. Solving gives x=2. Sagar's present age is 5x+6 = 16 years.