I like to use letters that remind me of what they stand for. So I use: n = the number of nickels p = the number of pennies $0.05n = the monetary value of the n nickels $0.01p = the monetary value of the p pennies Total value = $0.05n + $0.01p If the p pennies were turned into dimes, their monetary value would be $0.10p. If the n nickels were turned into pennies, their monetary value would be $0.01n. Total value would be = $0.10p + $0.01n. We set those values equal: $0.05n + $0.01p = $0.10p + $0.01n Solve for p in terms of n Drop the dollar marks and multiply every term by 100 to remove the decimals: 5n + p = 10p + n 4n = 9p= p So n must be divisible by 9 in order to divide evenly into 4n Then the value is 0 ≦ $0.05n + $0.01p < 2.00 0 ≦ 5n + p < 200 0 ≦ 5n + 4n/9 < 200 0 ≦ 45n + 4n < 1800 0 ≦ 49n < 1800 0 ≦ n < 36.73469388 0 ≦ n < 36 So n can equal 0, 9, 18, 27, 36 And since = p So p can equal , , , , That is, p can equal 0, 4, 8, 12, 16 So the 5 solutions are: 1. We can have 0 nickels and 0 pennies, and 0 coins. Total = $0.00 If the 0 pennies were turned into 0 dimes, their monetary value would be 0·$0.10 = $0.00. And, if the 0 nickels were turned into 0 pennies, their monetary value would be 0·$0.01. And the total would be $0.00. ----------------------------------------------------------- 2. We can have 9 nickels and 4 pennies, and 13 coins. Total = $0.49 If the 4 pennies were turned into 4 dimes, their monetary value would be 4·$.10 = $0.40. And, if the 9 nickels were turned into 9 pennies, their monetary value would be 9·$0.01 = $0.09. And the total would be $0.49. ----------------------------------------------------------- 3. We can have 18 nickels and 8 pennies, and 26 coins. Total = $0.98 If the 8 pennies were turned into 8 dimes, their monetary value would be 8·$.10 = $0.80. And, if the 18 nickels were turned into 18 pennies, their monetary value would be 18·$0.01 = $0.18. And the total would be $0.98. ----------------------------------------------------------- 4. We can have 27 nickels and 12 pennies, and 39 coins. Total = $1.47 If the 12 pennies were turned into 12 dimes, their monetary value would be 12·$.10 = $1.20. And, if the 27 nickels were turned into 27 pennies, their monetary value would be 27·$0.01 = $0.27. And the total would be $1.47. ----------------------------------------------------------- 5. We can have 36 nickels and 16 pennies, and 52 coins. Total = $1.96 If the 16 pennies were turned into 16 dimes, their monetary value would be 16·$.10 = $1.60. And, if the 36 nickels were turned into 36 pennies, their monetary value would be 36·$0.01 = $0.36. And the total would be $1.96. ----------------------------------------------------------- Edwin