Question 938885
Method 1:
Solve using a single equation:
  
Let d=number of nickels (worth 10 cents each)
then 23-d = number of nickels (worth 5 cents each)
  
We have total value
10d + 5(23-d) = 195 cents
  
Distribute and group like terms
10d + 115 -5d = 195 
5d = 195-115
5d = 80
d=16
Answer: So there are 16 dimes and 23-16=7 nickels.
Check: 16(10)+7(5)=160+35=195 cents = $1.95  checks.
  
  
Method 2: (can be done mentally)
Assume all coins are dimes, then value = 23*10 = 230 cents.
There is an excess of 230-195=35 cents.
So number of nickels = 35 cents / (10-5) cents = 7
Number of dimes  = 23-7 = 16 as as before.