mathematics
posted by kola .
the present age of a father and his son are in the ratio 10:3. if the son is 15 years old now, in how many years will the ratio of their age be 2:1?

present:
father  10x
son 3x
3x = 15
x = 5
son is now 15 and father is now 50
in t years,
(50+t)/(15+t) = 2/1
30+2t = 50+t
t = 20
in 20 years , the father will be 70 and the son will be 35
(which is in the ratio of 2:1 ) 
The arithmetic mean of x y and z is 6 while x y z t u v and w is 9 calculate the arithmetic mean of t u v and w.