To cut costs while maintaining the quality of education, one of the board members of a school district proposed to have the number of teachers vary directly as the number of students in a classroom. she proposed 12 teachers to teach a student body of 228 students. how many teachers would be needed if the school grows to 399 students?
a. 19 teachers
b. 21 teachers
c. 20 teachers
d. 20.9 teachers