You can put this solution on YOUR website! If john is twice as old as his son in 20 years the ratio of their ages will be 4:3,
what is John's son's current age?
:
let j = John's current age
Let s = Son's current age
: =
Cross multiply
3(j+20) = 4(s+20)
3j + 60 = 4s + 80
3j = 4s + 80 - 60
3j = 4s + 20
:
It said,"John is twice as old as his son"
j = 2s
Substitute 2s of j in the above equation
3(2s) = 4s + 20
6s = 4s + 20
6s - 4s = 20
2s = 20
s = 10 yrs is son's current age
then
2(10) = 20 yrs is John's present age
:
:
Check solution in 20 yrs
40/30 = 4/3
