Use equivalent fractions to combine and compare amounts with related denominators.
Example 1
A recipe uses 21 cup of milk, then another 32 cup. How many cups are used altogether? Give an exact fraction or whole number.
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Answer: 67
- Both amounts are parts of one cup. Express them in 6ths: 63 and 64.
- The total is 67=67 cup.
Example 2
A recipe uses 41 cup of milk, then another 83 cup. How many cups are used altogether? Give an exact fraction or whole number.
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Answer: 85
- Both amounts are parts of one cup. Express them in 8ths: 82 and 83.
- The total is 85=85 cup.
Example 3
Calculate 34−21. Give an exact fraction or whole number.
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Answer: 65
- Convert 21 to 63.
- Subtract the numerators: 68−3=65.