SOLUTION: A coin bank contains only nickels, dimes, and quarters. The value of the 31 coins in the bank is $2.80.There are twice as many nickels as dimes. Find the number of each type of coi

Question 542082: A coin bank contains only nickels, dimes, and quarters. The value of the 31 coins in the bank is $2.80.There are twice as many nickels as dimes. Find the number of each type of coin in the bank.
So far I have done: Dimes=x
Nickels=2x
Quarters=(31-x)
Dimes= 10 times x
Nickels= 5 times 2x
Quarters= 25 (31-x)
5(2x)+10x+25(31-x)=280
10x+10x+775-25x=280<-----doesn't look right.
I believe I am messing up on the quarters section.
Answer by jpg7n16(66) (Show Source): You can put this solution on YOUR website!
"So far I have done: Dimes=x" this part is right, though I like to use D for dimes
"Nickels=2x" Again, right.
"Quarters=(31-x)" This is wrong. What you are saying with this equation is that . But what about the nickels? should be:
or in your case

.
"Dimes= 10 times x" Correct
"Nickels= 5 times 2x" Correct
"Quarters= 25 (31-x)" Use above formula.

And solving:

And I believe you've got it from here! Hope this helps
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