Concept:Maintaining a constant ratio between students and teachers.Explanation:First, we find the ratio of students to teachers in the school.Ratio = Number of Students / Number of TeachersRatio = $45 / 3$Ratio = $15$ students per teacher.This means for every 15 students, there is 1 teacher.Now, 300 more students are enrolled. To maintain the same ratio, we need to find out how many teachers are required for these 300 students.Let $x$ be the number of additional teachers required.The ratio of new students to new teachers must be the same as the original ratio.So, $300 / x = 15$To find $x$, we can rearrange the equation:$x = 300 / 15$$x = 20$Therefore, 20 additional teachers are required.Answer:20