1 7/8
She ate 3/8 quarts of soup.
There are 2 1/4 quarts of soup.
So in order to solve it, you must make both denominators equal.
The GCF is 8, so 4×2=8
You must do the same with the nominator as well.
So, 1×2=2
Since 3/8 is bigger than 2/8, you must use a whole number. Lets take one.
It then becomes 1 10/8.
1 10/8 - 3/8= 1 7/8
Therefore, the answer is 1 7/8