If you cut both pizzas into eighths that means that each pizza has 8 pieces. For two pizzas cut in eighths that would be 16 pieces of pizza.
1/4 of one pizza is 2 pieces.
So 16 minus 2 pieces is 14 pieces.
If she ate another 3 pieces then we subtract that from 14.
14 minus 3 is 11 pieces.
There is 11 pieces of pizza left from the original 16 pieces.