Present ages of Sam and Amar are the ratio of 5: 4 respectively. Three years later, the ratio of their ages will become 8: 7 respectively. What is Amar's present age in years?

4 years

                          Sam   :   Amar

Present age     :    5    :     4

After 3 years    :    8    :    7

Ratio increased:    3    :    3  ( in 3 years)

So,

3R = 3 years

1R = 1 year

Therefore,

Present age of Amar = 4R = 4 × 1 = 4 year