SOLUTION: I have 30 coins consisting of 20c coins a 5c coins and my total is $3.45 how many 20c and 5c coins do I have?

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Question 1158483: I have 30 coins consisting of 20c coins a 5c coins and my total is $3.45 how many
20c and 5c coins do I have?
Found 2 solutions by josmiceli, Edwin McCravy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = number of 5c coins
Let +b+ = number of 20c coins
-----------------------------------------
(1) +a+%2B+b+=+30+
(2) +5a+%2B+20b+=+345+ ( in cents )
--------------------------------
(2) +a+%2B+4b+=+69+
Subtract (1) from (2)
(1) +-a+-+b+=+-30+
----------------------------
+3b+=+39+
+b+=+13+
and
(1) +a+%2B+13+=+30+
(1) +a+=+17+
------------------
number of 5c coins = 17
number of 20c coins = 13
-------------------------------
check:
(2) +5a+%2B+20b+=+345+
(2) +5%2A17+%2B+20%2A13+=+345+
(2) +85+%2B+260+=+345+
(2) +345+=+345+
OK

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
I have 30 coins consisting of 20c coins a 5c coins and my total is $3.45 how
many 20c and 5c coins do I have?
Let n = the number of 20c coins,
then the number of 5c coins are 30-n.

Then the total money is 20n + 5(30-n).

That must equal 345c

20n + 5(30-n) = 345

Solve that for n.  That will be the number of 20c coins.

Then subtract from 30 to find the number of 20c coins

Edwin