SOLUTION: Karla's credit card bill is 420.90 part of the bill is previous month balance, part is new charges and part is from a late fee of 39.00. The previous balance is 172.40 less than th

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Question 1085480: Karla's credit card bill is 420.90 part of the bill is previous month balance, part is new charges and part is from a late fee of 39.00. The previous balance is 172.40 less than the new charges. How much is the previous balance and how much is in new charges?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = the previous balance
Let +b+ = the new charges
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(1) +a+%2B+b+%2B+39+=+420.9+
(2) +a+=+b+-+172.4+
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(1) +a+%2B+b+=+381.9+
(2) +-a+%2B+b+=+172.4+
-------------------------
+2b+=+554.3+
+b+=+277.15+
and
(2) +a+=+b+-+172.4+
(2) +a+=+277.15+-+172.4+
(2) +a+=+104.75+
The previous balance is $104.75
The new charges are $277.15
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Check the answers
(1) +a+%2B+b+%2B+39+=+420.9+
(1) +104.75+%2B+277.15+%2B+39+=+420.9+
(1) +381.9+%2B+39+=+420.9+
(1) +420.9+=+420.9+
OK