Answer:
There will be 330 7th grade students in this middle school this year.
Step-by-step explanation:
Last year enrollment = 150 students
As the enrollment increased by 120%.
i.e.
Number of Percentage increase = 120% × 150 = 120/100 × 150
                            = 1.2 × 150
                            = 180
Thus,
Total students this year = No. of Percentage increase + Last year students
                    = 180+150
                    = 330 students
Therefore, there will be 330 7th grade students in this middle school this year.