A father is three times as old as his son. After fifteen years the father will be twice as old as his son's age at that time. Hence the father's present age is

Step-by-step explanation:

let present age of father=y

present age of son=x

then y=3x

after 15 years age of father=y+15

and age of son=x+15

∴y+15=2(x+15)

y+15=2x+30

y-2x=30-15

y-2x=15

∴3x-2x=15

x=15

y=3x=15×3=45

father's present age=45 years

where's the diagrams?