1. 비와비율 https://quiz.zep.us/play/r75Goa
2. 비와비율 https://quiz.zep.us/play/r7E7zO
3. 여러가지 그래프 https://quiz.zep.us/play/JdWlna
4. 여러가지 그래프 https://quiz.zep.us/play/QaNRAr