Q. Ten years back, Rohan’s age was four times the age of his son. Ten years hence, Rohan’s age will become twice the age of his son. Find out the sum of the present ages of Rohan and his son (in years).
Let the age of the son be x years.
Now,10 years back:(R–10)=4(x–10)
→R–4x=−30….Eqn. (i)
Also,10 years hence:(R+10)=2(x+10)
→R−2x=10…..Eqn. (ii)
Subtracting eqn (i) from (ii), we get
2x=40→x=20.Substituting this value in eqn.(ii),we get:
R–2(20)=10 or R=10+40=50 years
Now,R=x=50+20=70 years.