Aloaf of bread is cut into slices of equal size. some of the loaf is used in a recipe and 2/12 of the loaf is used to make a sandwich. the remaining 7/12 of the loaf is put into the refrigerator

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Fraction of bread used in the recipe is 3/12 which can be further simplified into 1/4

Explanation:
The original loaf of bread is 100% complete (no fraction is taken from it yet). This means that the value of the original loaf is 12/12

Now, assume that the fraction used in the recipe is x
We know that:
2/12 of the loaf was used in making a sandwich
7/12 of the oaf was put in the refrigerator

Therefore:
complete loaf = fraction used in making a sandwich + fraction used in making recipe + fraction put in refrigerator
12/12 = x + 2/12 + 7/12
12/12 = x + 9/12
x = 12/12 - 9/12
x = 3/12 

Hope this helps :)

15 cm is the answer to your question