Bob and Alice have together a sum of $103$ years old. In $4$ years, Alice will have $2$ times the age of Bob.
What age will they have ?
I'm trying different equation and doing my substitution but I can't get a valid answer (a integer).
$$ x+y = 103 ,$$
$$ (x+4) + (y+4) = 2x $$
Thanks for help, it's appreciated !