Jenny starts a game with twice as many marbles as Keiko. Jenny gives keiko 5 marbles, but she still has 10 more than keiko. How many marbles did Jenny have to start with

Jenny has 40 marbles and Keiko has 20. When Jenny gives Keiko 5 of her marbles, now Jenny has 35 marbles and Keiko has 25. Jenny had twice as many marbles at first with 40 and after giving 5 to Keiko, Jenny has 10 more then Keiko. So answer is 40!