SOLUTION: A collection of nickels and dimes contains 9 fewer nickels than dimes. The total value of the collection is $3.15. How many nickels are in the collection? I tried: 3.15=(0.10)

Question 1023045: A collection of nickels and dimes contains 9 fewer nickels than dimes. The total value of the collection is $3.15. How many nickels are in the collection?
I tried:
3.15=(0.10)d+(0.05)n
3.15=0.10d+0.05-9d
I got some weird answer like .715 for how many dimes were there. I'm lost.
Found 2 solutions by addingup, solver91311:
Answer by addingup(3677) (Show Source): You can put this solution on YOUR website!
d = n+9
0.05n+0.10d = 3.15 substitute for d:
0.05n+0.10(n+9) = 3.15
0.05n+0.10n+0.90 = 3.15
0.15n = 2.25
n = 15 There are 15 nickels in the collection
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

is correct, but you are given that so:

.

Now solve for .

Note that

has the same solution set but is less confusing and less mistake-prone because of the elimination of the decimals.

John

My calculator said it, I believe it, that settles it

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