math
posted by Mary .
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