Eliza brought 3 pans of homemade fruit bars to school. her classmates ate 7/12 of each pan. eliza gave 1 whole pan of the leftover fruit bars to the school's secretaries and took the rest home. explain how to find how much of a pan of fruit bars eliza took home.

To solve this, you have to take 7/12 out of each pan first, so how to do that is to divide each pan into 1/12. So you did that, and all three pans equal 36/12. Great. Eliza has 36/12 fruit bars. 
Now, you see that the classmates at 7/12 out of EACH. To find that out, you just multiply 7/12 by 3 which is 21/12. Subtract 21/12 from 36/12 since the classmates ate 21/12 out of the total and you get 15/12.
Now she gave 1 pan to the secretaries, which is 12/12, so you subtract that from the 15/12 you have left over. That's 3/12.

And she brought 3/12 home. You can simplify that into 1/4.

What’s the equation you are trying to solve to get x?