Alemon bar recipe calls for 1 1/2 cups of flour for every 1/3 teaspoon of lemon zest. could you increase the recipe proportionately by using 15 cups of flour and 6 teaspoons of lemon zest?

No. To have gotten to 15 cups of flour, I multiplied by 10. When I multiplied 1/3 by 10, however, it did not show 6. It showed 3.333...

Your answer is No

1/3 + 1/3 ≠ 2/6 because 1/3 alone = 2/6  

step by step explanation:

1/3 + 1/3 = 2/3       2/3=4/6