200,000,000 that your answer
You can’t really know the y value unless you’re told that they’re both directly proportional. if so, then check out the pic
Let Marc's age be x. If Jeanine is twice as old as Marc, then her age will be 2x. If their ages added together are 24, then you can create the following equation:
2x + x = 24
3x = 24
x = 8
Remember that x is Marc's age. So if Marc is 8, and Jeanine is twice as old, she will be 16.