Ram : Mohan = 4 ∶ 5 Mohan : Anil = 5 ∶ 6 Ram : Mohan : Anil = 4 ∶ 5 ∶ 6 Let the present ages of Ram, Mohan and Anil be 4x , 5x and 6x respectively, where x is any constant, then, If sum of their ages be 90 years 4x+5x+6x=90 ⇒15x=90 ⇒x=6 ∴ Present age of Mohan =5x=5×6=30 years. Hence, the present age of Mohan is 30 years.