Final answer:
To determine the amount of sugar needed for 5 cups of flour, a proportional relationship is established from the recipe's ratio, leading to approximately 1.67 cups of sugar.
Step-by-step explanation:
To find out how many cups of sugar should be used if a recipe calls for 5 cups of flour, we need to set up a proportion based on the given relationship: 2 cups of flour per 2/3 cup of sugar. First, we compare the proportions: 2 cups of flour is to 2/3 cup of sugar as 5 cups of flour is to x cups of sugar. The proportion is 2/2/3 = 5/x. We cross multiply to find the value of x, resulting in 2x = 2/3 * 5. Simplifying this gives us x = (2/3) * (5/2), which equals 5/3 or approximately 1.67 cups of sugar.