Final answer:
Robin originally had 9 1/4 cups of flour on Saturday.
Step-by-step explanation:
To find out how much flour Robin originally had on Saturday, we need to subtract the amount of flour she had left at the end of the day from the total amount of flour she used.
Robin made two batches of each item, so she used 1 3/4 cups of flour for bread, 2 cups for muffins, and 1 1/2 cups for pancakes.
Therefore, the total amount of flour she used is 2*(1 3/4) + 2*2 + 2*(1 1/2) = 3 1/2 + 4 + 3 = 10 1/2 cups.
Since she had 1 1/4 cups of flour left, we can subtract this from the total amount to find the original amount of flour: 10 1/2 - 1 1/4 = 9 1/4 cups.