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4-43.

Find each sum or difference without a calculator.

  • Find a common denominator.

  • To add the fractions together, start by finding the least common multiple of 3 and 10. Then use that number as a common denominator. This table lists multiples of 3 and 10.

  • LCM is 30. Rewrite each fraction to have a denominator of 30 by using Giant Ones, as shown below. Can you add the fractions now?

  1. Whenever adding or subtracting decimals, be sure to line up the decimal point! It may help to write this problem like this:

    Also, remember that the decimal point will fall in the same place in your answer.

  2. . Rewrite  as an improper fraction. Then follow the example in Part (a).