This isn't my homework. It's a math problem I picked up while reading a book to promote clearer thinking. I know the answers are 56 and 42, but I'm wondering about how to restate the second equation in the system with this problem: 'the ages of a man and his wife together are 98. He is twice as old as she was when he was the age she is today. What are their ages?'
Obviously, the first equation would be \[x + y = 98\]. Does one state the second equation as \[x/2 = y - z\]? But then wouldn't that add another variable?