You can
put this solution on YOUR website!We have two facts to start with
1) the number of nickels and the number of dimes add up to 35
2) the value of the nickels and dimes add up to $3.30
Let's call the number of nickels
n and the number of dimes
d. The number of coins add up to 35 and the value of the nickels is $0.05n and the value of the dimes is $0.10d. We can convert the two facts to a mathematical representation as follows:
1) n + d = 35
2) $0.05n + $0.10d = 3.30
Subtract n from both sides of the first equation to get
d + n - n = 35 - n
d = 35 - n
Now substitute d = 35 - n into the second equation:
0.05n + 0.10(35 - n) = 3.3
0.05n + 3.5 - 0.10n = 3.3
3.5 - 0.05n = 3.3
Subtract 3.3 from either side
3.5 - 0.05n - 3.3 = 3.3 - 3.3
0.2 - 0.05n = 0
Add 0.05n to either side to get
0.2 - 0.05n + 0.05n = 0.05n
0.2 = 0.05n
divide both sides by 0.05 to get:

=
So, n = 4. Since d + n = 35 and n = 4, we know d + 4 = 35. Subtract 4 from either side to get d = 31.
The answer is 4 nickels and 31 dimes.
To see that this is true, figure out how much 4 nickels and 31 dimes are worth. The 4 nickels add up to $0.20 and the 31 dimes add up to $3.10, the nickels and dimes add up to $3.30. This is exactly what the problem says.