A dough recipe calls for 3 cups of flour and 1-1/4 cups of water. You want to use the same ratio of flour to water to make a dough with 10 cups of flour. How much water should you use?

a. Solve this problem by setting up an equation in which you set two fractions equal to each other.

b. Interpret the two fractions that you set equal to each other in part (a) in terms of the recipe.

c. Why does it make sense to cross-multiply the two fractions in part (a)? What is the logic behind the procedure of cross-multiplying?

d. Now solve the problem of how much water to use for 10 cups of flour in a different way, by using the most elementary reasoning you can. Explain your reasoning clearly