Hello! I would love to help!
Okay, let's first figure out what the problem is asking us. Basically, we need to subtract 4/6 from 5/6 to find the extra left over.
Let's do it!
We need to do 5/6-4/6
To do this, subtract the numerators, or top numbers of each fraction.
The top numbers are 5 and 4
5-4=1
Now, put the new numerator over 6, the common denominator.
1/6
So, your answer is 1/6 cup extra oil.
Hope this helped! Comment if you have questions!