A box contains nickels, dimes and pennies worth $8.40. The number of dimes is six less than twice the number of pennies and there is an equal number of dimes and nickels. How many nickels are there in the box? Type in your numerical answer only; do not type any letters or words with your answer.
Ok I got that...
d + p + n = 8.40
n = d
From there I dont know how to find the value of nckels...
2007-12-16 09:04:15 · 2 answers · asked by Tiffany R 1 in Science & Mathematics ➔ Mathematics
the number of dimes is six less than twice the number of pennies
1) d = 2p - 6
there is an equal number of dimes and nickels.
2) n = d
worth $8.40
1p + 5n + 10d = 840 {cents}
From equations 1 & 2 you see that both n and d can be replaced by 2p - 6
1p + 5(2p - 6) + 10(2p - 6) = 840
p + 10p - 30 + 20p - 60 = 840
31p - 90 = 840
31p = 930
p = 30
1) d = 2(30) - 6 = 60 - 6 = 54
2) n = d = 54
check
1(30) + 5(54) + 10(54) = 840
30 + 270 + 540 = 840
840 = 840
2007-12-16 09:16:45 · answer #1 · answered by Anonymous · 0⤊ 0⤋
You're 1 for 3.
Yes, N = D.
Also, D + 6 = 2P.
But the money value equation is 840 = 10 D + 1 P + 5 N.
The solution turns out to be P = 30, N = D = 54.
2007-12-16 13:03:57 · answer #2 · answered by Curt Monash 7 · 0⤊ 0⤋