Question 175417
Let x = son's age
4x = father's age


x-10 = son's age 10 years ago
4x-10= father's age 10 years ago


x-10 + 4x-10=60
5x-20=60
5x=80
x=16  son's age now
4x=64 father's age now (or was that his grandfather??)


Check:  10 years ago, son was 6 and father was 54, and the sumof their ages is 60.  


R^2