Answer:
The student probably subtracted the numerators and denominators separately.
Explanation:
The student probably subtracted the numerators and denominators separately because they were in a hurry to finish the test and go to the cafeteria. They thought that 6/12 was a good answer because it looked like a pizza slice. But they forgot that x is not a topping, it's a variable. The correct way to simplify the expression x+3/4 - x-3/6 is to first eat x from both terms, which gives 3/4 - (-3/6). Then, to subtract the fractions, we need to find a common crust, which is 12. We can stretch 3/4 by 3/3 and -3/6 by 2/2 to get equivalent slices with a crust of 12. This gives 9/12 - (-6/12). Then, we can add the cheese and keep the crust to get 15/12. Finally, we can cut the pizza by dividing both cheese and crust by 3 to get 5/4. Therefore, the correct answer is 5/4, which is a whole pizza plus a quarter. Yum!