For (A.) Get a common denominator, 40/12 - 9/12 = 31/12 or (2 and 7/12)
For (B.) Get a common denominator, 24/15 - 10/15 = 14/15 (Simplified)
For (C.) Get a common denominator, 51/30 - 25/30 = 26/30 or (13/15)
For (D.) Get a common denominator, 14/6 - 9/6 = 5/6 (Simplified)
Hope this helps!
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Answer: 17mm
Step-by-step explanation:

One-eighth represents one part of a whole that consists of eight units, but one-twelfth represents one part of a whole that consists of 12 units. Fractions are made up of numerators and denominators. Numerators are the top numbers and denominators are the bottom numbers. The numerator is the number that represents the part of a whole. The denominator is the total number of parts.
<span>A) y = 7</span>
I hope this helps. (:
14 cups. He's making three pizzas so he needs 3 pizzas' worth of flour. For one, he needs two. So he needs six cups in total. 20-6=14