Final answer:
To find the number of students in Mr. Oakley's class, we set up the equation 0.9x = x - 5 and solved for x, which results in x = 50 students. The correct answer is (a) x - 5.
Step-by-step explanation:
Mr. Oakley has x students in his class, and 90% of the students will go on the field trip. If all but 5 of his students plan to go, this means that the 90% of the class that is going on the trip is equivalent to x minus 5 students because 5 students are not going. To solve for x, we set up the equation 0.9x = x - 5.
Now, we can solve for x:
- Add 5 to both sides: 0.9x + 5 = x.
- Subtract 0.9x from both sides: 5 = x - 0.9x.
- Combine like terms: 5 = 0.1x.
- Divide both sides by 0.1 to find x: 5 / 0.1 = x.
- x = 50. Therefore, there are 50 students in Mr. Oakley's class.
The correct answer to the question is (a) x - 5 because this expression represents the number of students going on the field trip which is 90% of the total number of students.