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When cooking a couple of recipes, you may need to use the same ingredient more
than once. To make sure that you have enough of the ingredient at home, you
will need to add the quantities together. For example, you may need 3/4 cup
of sugar and 1/2 cup of sugar. Adding these fractions requires you to find a
common demoninator, which in this case will be 4. So the total amount needed
would become 3/4 + 2/4 = 5/4 or 1 1/4 cups of sugar. Notice that the 1/2 was
rewritten as 2/4 so the sum of the two quantities could be found.