Question

Anthony has been saving nickels (N), dimes (D), and quarters (Q) over the last year. ​He knows that he has twice as many nickels as quarters. When he takes the coins to the change machine to exchange them for paper money, ​he learns that he has 260 coins that total $29.75. Determine the number of each type of coin Anthony saved.

Answer 1

75 number of quarters

150 number of nickels

35 number of dimes

Explanation:

Let x, y and z be the amount of quarters, nickel and dimes respectively.

​he learns that he has 260 coins, thus;

x + y + z = 260 - - - (1)

Now, we are told that he has twice as many nickels as quarters.

Thus, number of nickels = 2x

y = 2x - - - (2)

From online research, we have the following cost;

1 quarter = $0.25

1 nickel = $0.05

1 dime = $0.1

Total cost is $29.75. Therefore;

0.25x + 0.05y + 0.1z = 29.75 - - - (3)

Put 2x for y in eq (1) and eq (3) to get;

x + 2x + z = 260

3x + z = 260 - - - (eq 4)

0.25x + 0.05(2x) + 0.1z = 29.75

0.25x + 0.10x + 0.1z = 29.75

0.35x + 0.1z = 29.75 - - - (eq 5)

From eq(4), z = 260 - 3x

Thus;

0.35x + 0.1(260 - 3x) = 29.75

0.35x + 26 - 0.3x = 29.75

0.05x = 29.75 - 26

0.05x = 3.75

x = 3.75/0.05

x = 75

So, z = 260 - 3(75)

z = 260 - 225

z = 35

Since y = 2x,

Then,y = 2(75) = 150

Thus,we have;

75 number of quarters

150 number of nickels

35 number of dimes