A vending machine takes only nickels and dimes. At the end of the day there were three times as many nickels as dimes and a total of $25.00. How many of each coin were in the machine?
What are the equations, and how do you solve this?
2007-02-08 12:56:26 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
d = number of dimes
3d = number of nickels (3 times as many dimes)
10d + 5(3d) = 2500 (cents equation)
10d + 15d = 2500
etc
2007-02-08 13:04:32 · answer #1 · answered by hayharbr 7 · 0⤊ 0⤋
let N = number of Nickels
let D = number of Dimes
N = 3D (three times as many nickels as dimes)
5N + 10D = 2500 (nickels are 5 cents, dimes are 10, all together 2500 cents)
5(3D) + 10D = 2500 (replacing N with 3D)
15D + 10D = 2500
25D = 2500
D = 100
N = 300
2007-02-08 21:03:41 · answer #2 · answered by Anonymous · 1⤊ 0⤋
x = number of nickels
y = number of dimes
3y = x (3 times the number of dimes equals the number of nickels)
.05x + .10y = 25 (dollar values.)
.05(3y) + .10y = 25 (subs. eqn 1 into eqn 2)
.15y + .10y = 25
.25y = 25
y = 100 dimes
x = 300 nickels (subs. y = 100 into eqn 1)
2007-02-08 21:05:16 · answer #3 · answered by Milton's Fan 3 · 0⤊ 0⤋
n = 3d
.05n + .1d = 25
You would solve by substitution. Plug "3d" for "n" in the 2nd equation.
.05(3d) + .1d = 25
.15d + .1d = 25
.25d = 25
d = 100
Now go back to your first equation to solve for n.
n = 3d
n = 3(100) = 300.
300 nickels, 100 dimes =]
2007-02-08 21:03:54 · answer #4 · answered by teekshi33 4 · 0⤊ 0⤋
3N = D
N + D = 25
2007-02-08 21:03:38 · answer #5 · answered by mehran_kimi 2 · 0⤊ 1⤋