SOLUTION: Does anyone know the proper formula for this word problem? I figured out the answer but could not figure out how to properly put it in formula format: There are 10 coins consis

Algebra ->  Expressions-with-variables -> SOLUTION: Does anyone know the proper formula for this word problem? I figured out the answer but could not figure out how to properly put it in formula format: There are 10 coins consis      Log On


   

Question 163273: Does anyone know the proper formula for this word problem? I figured out the answer but could not figure out how to properly put it in formula format:
There are 10 coins consisting of nickles and dimes. There is 80 cents total. How many nickles and dimes are there?
So far I have tried: n+d=80 and n(5)+d(10)=80
Thank you! ~Melyssa
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Well Melyssa, you are on the right track! Let n = number of nickels and d = number of dimes.
Your two equations should be:
1) n%2Bd+=+10 and...
2) 0.05n%2B0.1d+=+0.8 Substitute n+=+10-d from equation 1)
0.05%2810-d%29%2B0.1d+=+0.8 Combine like-terms and simplify.
0.5-0.05d%2B0.1d+=+0.8
0.5%2B0.05d+=+0.8 Subtract 0.5 from both sides.
0.05d+=+0.3 Divide both sides by 0.05
d+=+6 and n+=+10-d so n+=+4
So there are 6 dimes and 4 nickels.
Check:
6($0.10)+4($0.05) = $0.60+$0.20 = $0.80