father is 50
Julia's age : a year-old
Wendy is twice the age of Julia
= > Wendy = 2a year-old
Dad's age : b year-old
" The man is now five times as old as Wendy " b / 2a = 5 <=> b = 10a
" In four years he will be six times as old as Julia " :
( B + 4 ) / (a + 4 ) = 6 + 4 = 6. <=> b (a + 4 )
<=> B = 6a +20
I have two equations :
6a + b = 20
b = 10a
= > 10a = 6a + 20 - > a = 5
- > B = 10a = 50
