Example

Solving a Coin Mixture Problem: Pennies and Nickels

Apply the seven-step problem-solving strategy and the total value of coins model to a coin mixture problem in which the relationship between the two coin counts involves both multiplication and addition.

Problem: Danny has $2.14 worth of pennies and nickels in his piggy bank. The number of nickels is two more than ten times the number of pennies. How many nickels and how many pennies does Danny have?

  1. Read: The coins are pennies (worth $0.01) and nickels (worth $0.05). Total value is $2.14.
  2. Identify: Find the number of pennies and nickels.
  3. Name: Let pp = the number of pennies. The number of nickels is 10p+210p + 2. Organize in a table:
TypeNumberValue ($)Total Value ($)
Penniespp0.010.01p
Nickels10p+210p + 20.050.05(10p+2)0.05(10p + 2)
Total2.14
  1. Translate: Add the total values to equal the overall total: 0.01p+0.05(10p+2)=2.140.01p + 0.05(10p + 2) = 2.14.
  2. Solve:
  • Distribute: 0.01p+0.50p+0.10=2.140.01p + 0.50p + 0.10 = 2.14
  • Combine terms: 0.51p+0.10=2.140.51p + 0.10 = 2.14
  • Subtract 0.10: 0.51p=2.040.51p = 2.04
  • Divide by 0.51: p=4p = 4
  • Find nickels: 10(4)+2=4210(4) + 2 = 42
  1. Check: 4(0.01) + 42(0.05) stackrel{?}{=} 2.14 -> 0.04+2.10=2.140.04 + 2.10 = 2.14. checkmark
  2. Answer: Danny has 4 pennies and 42 nickels.
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Updated 2026-06-29

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