Final answer:
The correct equation representing the relationship between the number of loaves of cranberry bread (b) and cups of flour (f) is b = 10/3 f, based on Mary's recipe ratio.
Step-by-step explanation:
Let's find the correct relationship between b loaves and f cups of flour based on Mary's recipe. According to the information provided, Mary uses 6 and 2/3 cups of flour to make 2 loaves of cranberry bread. This means that the ratio of cups to loaves is 6.67/2, which simplifies to 20/6.
We can set up a proportion to find the relationship where f is proportional to b. This gives us the equation f / b = 20/6, or after multiplying both sides by b, we get f = (20/6) * b. Simplifying this fraction gives us f = (10/3) * b, which matches option 4.
Therefore, the correct equation that represents the relationship between b and f is b = 10/3 f.