Math homework

Mom asked dad to give Calvin a hand with his math homework. It looked like he was having trouble with a word problem.

Beth had four baseball cards. Then bought three more. David had three baseball cards. Then he bought four more. Who had more baseball cards.

Calvin had written Beth.

"Calvin, look at this again. Does one of them have more than the other?"

"Not now. They have the same now, but Beth HAD more."