You can put this solution on YOUR website! Usually you look for an equation involving the number of different coins.
Next you look for a 2nd equation involving the VALUE of the different coins (weigh each number of coins by its individual value).
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Example: I have 20 coins total. There are only nickels and dimes. The total value of the coins is $1.90.
How many of each coin do I have?
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Let d = number of dimes
Let n = number of nickels
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d+n = 20 (from 20 coins total)
10d + 5n = 190 (this eqn comes from the total value given, notice how I weigh each coin type, units are in cents)
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d = 20-n (from rearranging the first eqn)
10(20-n) + 5n = 190 (substituted for "d" in 2nd eqn)
200 - 10n + 5n = 190
10 = 5n (subtracted 190 from both sides, added 10n to both sides)
10/5 = n (divided both sides by 5)
2 = n
n=2 —> implies —> d=20-2 = 18
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Answer: 18 dimes, 2 nickels.
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Always check: 18*10 + 2*5 = 180 + 10 = 190 (= $1.90) , so we're good.
You will find there the lessons for all levels - from introductory to advanced,
and for all methods used - from one equation to two equations and even without equations.
Read them and become an expert in solution of coin problems.