Task: Question Answering
Input (English): Problem: the present ratio of students to teachers at a certain school is 70 to 1 . if the student enrollment were to increase by 50 students and the number of teachers were to increase by 5 , the ratio of students to teachers would then be 25 to 1 . what is the present number of teachers ? 
Options: a ) 2 , b ) 8 , c ) 10 , d ) 12 , e ) 15
Output (English): a