Ms. Kawashita is a mathematics teacher at Ishida junior high school.
The math exam is tomorrow, but Kaito doesn't seem to have any sense of urgency.
Dear Math, please grow up and solve your own problems by yourself.
The study of numbers is mathematics (or math).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.