Answer:
about 21 students
Explanation:
total students: 150 students enrolled
recognize all letters: 6/7 of the students
To find 1/7 of the students: divided the 150 by 7
150/7 = 21.4285 this is for 1/7th of students
since 1/7th of the students need to learn the alphabet (7/7 - 1/7 = 6/7)
OR
150/7 = 21.4285 this is for 1/7th of students
150/7 x 6 = 128.57 this is for 6/7th of students
150 - 128.57 = 21.4285