A collection of 24 coins, consisting of nickels, dimes, and quarters, has a value of $3.40. If there are twice as many quarters as nickels, and one-third as many nickels as dimes, how many coins of each kind are there?
Let the number of nickels, dimes, and quarters, be N, D, and Q, respectively
Then we get: N + D + Q = 24 -------- eq (i)
Also, Q = 2N
As there are as many nickels as dimes, it follows that: D = 3N
N + 3N + 2N = 24 ------ Substituting 2N for Q, and 3N for D in eq (i)
6N = 24
N, or number of nickels = , or
Number of dimes: 3(4), or
Number of quarters: 2(4), or
As seen, the value of these 24 coins was not needed. In other words, it was totally unnecessary to include it!