Let's denote the amount of flour in the original recipe as \( F \) cups.
The original recipe makes 4 loaves and calls for:
- 2 cups of sugar,
- \( F \) cups of flour.
The total amount of flour and sugar in the original recipe is: \[ F + 2 \text{ cups (sugar)} = \text{Total amount in the original recipe} \]
Since the revised recipe calls for 2.5 cups (which is 2 1/2 cups) of flour and sugar combined to make 1 loaf, we can interpret this as follows:
The modified recipe is now meant to be one-fourth of the original recipe (since it originally makes 4 loaves). Thus, for 1 loaf, the total amount of flour and sugar combined should be: \[ \text{Total amount for 1 loaf} = \frac{F + 2}{4} \]
According to the revised recipe, this total amount is given as: \[ \frac{F + 2}{4} = 2.5 \]
Next, we can solve for \( F \). First, we'll multiply both sides by 4: \[ F + 2 = 2.5 \times 4 \] \[ F + 2 = 10 \]
Now, subtract 2 from both sides to find \( F \): \[ F = 10 - 2 \] \[ F = 8 \]
Thus, the amount of flour in the original recipe is: \[ \boxed{8 \text{ cups}} \]