Hello there! Your answer is approximately 14 students.
To solve this question, you want to start by finding 40% of 24. To do this, convert 40% into a decimal (divide by 100) and multiply by 24.
24 x 0.40 = 9.6.
But - you can't have 9.6 of a student. So, we round up to 10.
Note that the question asks how many students <em>still need to complete</em> their assignment, meaning we are looking for the ones that haven't finished. We found the amount for students that <em>have</em> finished, so subtract that from the total to see approximately how many still have to finish.
24 - 10 = 14
So, this means approximately 14 students still need to complete their assignment.
I hope I could help you, have a great rest of your day! :D