posted by Mary on .
Mr. Chang and his wife together had an unpaid balance of $500 on their credit cards for one month. THe bank that issued Mr. Chang's credit card charges an intrest rate of 1.25% a month and his wife's interest is 1.5 per month. If the total interest finance charge was $6.75 how much was each unpaid balance? Write an equaiton for the finance chare and the balance.
If Mr. C owes X, Mrs. C owes 500 - X.
The monthly interest paid is
0.0125X + 0.015*(500 - X) = 6.75
1.25X + 1.5(500 -X) = 675
75 = 0.25 X
Complete the solution for X. Then compute 500 - X