Answer:
30 students not take bus to school .
Step-by-step explanation:
As given
Bill is in a class of 15 boys and 35 girls.
Total number of students in the class = Number of boys + Number of girls
= 15 + 35
= 50
As given
40% of the students in the class take the bus to school.
40% is written in the decimal form.

= 0.40
Number of students take bus to school = 0.40 × Total students in class.
= 0.40 × 50
= 20
Thus
Students not take bus to school = Total students - Number of students take bus to school
= 50 - 20
= 30
Therefore 30 students not take bus to school .