a merchant has two loans totaling $25,000. the simple interest rates are 7% and 8%. if the annual interest charge on the 7% loan is $520 more than on the 8% loan, how much did he borrow at each rate?

Answer 1

.07X + .08(25,000-X) = total interest on 25,000= 1,832

.07X = 520 + .08(25,000-X)

.07X = 520 + 2,000 - .08X

.15X = 2,520

X = 2,520/.15 = $16,800 invested at 7%

and 25,000-16,800 = $8,200 invested at 8%

.07(16,800)= 1176

.08(8,200) = 656

1176 - 656 = 520