Zach borrowed $50,000 to buy a car, put a down payment on a house, and pay for student loans. Some of the money was borrowed at 5%, some at 6% and some at 7%. How much was borrowed at each rate if the annual interest owed was $3,150 and the amount borrowed at 5% was three times the amount borrowed at 6%?

Thank you

1 answer

amount borrowed at 6% ---- x
amount borrowed at 5% = 3x
amount borrowed at 7% = 50000 - 4x

solve for x

.06x + .05(3x) + .07(50000-4x) = 3150
times 100
6x + 15x + 7(50000-4x) = 315000
take over.