Mr. Carroll and Ms. Clark are teaching their classes how to write in cursive. Mr. Carroll has already taught his class 7 letters. The students in Ms. Clark's class, who started the unit later, currently know how to write 2 letters. Mr. Carroll plans to teach his class 4 new letters per week, and Ms. Clark intends to cover 5 new letters per week. Eventually, the students in both classes will know how to write the same number of letters. How many letters will the students know? How long will that take?
