.
You can solve it MENTALLY, without using equations.
For it, take (mentally) 4 dimes from the collection, for a moment.
Then you will have equal number of dimes and nickels in the updated collection which worth is 85 - 4*10 = 45 cents.
You can combine dimes and nickels in sets, each containing one dime and one nickel.
The each set worth is 10+5 = 15 cents, and the number of sets is 3 = .
So, the updated collection has 3 dimes and 3 nickels.
Hence, the original collection consists of 3+4 = 7 dimes and 3 nickels.
Solved.
There is entire bunch of lessons on coin problems
- Coin problems
- More Coin problems
- Solving coin problems without using equations
- Kevin and Randy Muise have a jar containing coins
- Typical coin problems from the archive
- More complicated coin problems
- Solving coin problems mentally by grouping without using equations
- Santa Claus helps solving coin problem
in this site.
You will find there the lessons for all levels - from introductory to advanced,
and for all methods used - from one equation to two equations and even without equations.
Read them and become an expert in solution of coin problems.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Coin problems".