What did I do wrong? 'Warren has 40 coins in nickels, dimes,

Warren has 40 coins (all nickels, dimes and quarters) worth $4.05. He has 7 more nickles than dimes. How many quarters does he have?

dimes: 10n + 7
nickles: 5n
quarters: 40 - (2n + 7)25

10n + 7 + 5n + 40 - (2n + 7)25 = 405
15n + 47 - 50n + 175 = 405
-35n + 222 = 405
-35n = 608

I can't divide that out because I would get a fraction.

N+D+Q = 40 /* Forty Coins */
5N+10D+25Q = 405 /* Worth of 40 Coins */
N = D + 7 /* Nickles and Dimes */

Re: what did i do wrong?

santasad13 said:

warren has 40 coins( all nickels, dimes and quarters) worth 4.05
he has 7 more nickles than dimes. how many quarters does he have?

Click to expand...

d = dimes
n = nickels
q = quarters

n = d + 7

q = 40 - d - n = 40 - d - d - 7 = 33 - 2d

5(d + 7) + 10d + 25(33 - 2d) = 405

carry on, Santa!

oh. i see what i did now. thank you guys so much!!!!!!