alleryStart learning →One number is five more than another. The sum of the numbers is 21. Find the two numbers.
A7 and 14
B5 and 16
C9 and 12
D8 and 13
Answer & Solution
Correct answer: D. 8 and 13
1. Let n equal the first number, so the second number is n plus 5.
2. The sum of the two numbers translates to n plus (n plus 5) equals 21.
3. Combine like terms: 2n plus 5 equals 21.
4. Subtract 5 and divide by 2 to get n equals 8, so the first number is 8 and the second is 13.
5. Check: 8 plus 13 equals 21, and 13 is indeed five more than 8.
_Source: OpenStax Elementary Algebra (CC BY 4.0), Ch 3 "Math Models", section 3.1 Use a Problem-Solving Strategy_
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