Answer: 0.4176 cups of flour
Step-by-step explanation: First you'll need to convert both amounts to the same denominator, using their LCM, which is 24. 1/3 x 8 = 8/24, 7/8 x 3 = 21/24. Then calculate what you need to multiply 21/24 with to get 24/24, 21/24 = 0.875 1.000- 0.875 = 0.125. Finally, multiply 1/3 by 0.125 which is 0.416... / 0.4167, so you'll need 0.4167 cups of flour, or 4,167/10,000 of a cup os flour.