Question 1140785
As I understand the problem, suppose she had 1 unit of flour, and now has 3/4 left.  Then she used 1/4 a unit of flour.
Because she used the same amount of sugar, she used 1/4 a unit of sugar as well.
But 3/8 of a unit of sugar is left.

So she started with 1 5/8 units of both, 1 of flour and 3/8+1/4=5/8 of a unit of sugar.
This is 13/8 units of ingredients

She used 2/4 or 4/8 units, 1/4 for each
She used 4/8 divided by 13/8 or 4/13 of the total amount.