In planning her​ retirement, Liza deposits some money at2 ​% ​interest, with twice as much deposited at ​3.5%. Find the amount deposited at each rate if the total annual interest income is ​$900.

Answer 1

.02x + .035(2x) = 900

.02x +.07x = 900

.09x = 900

x = 900/.09 = 100/.01 = $10,000 invested at 2%

2x = $20,000 invested at 3.5%

.02(10) + .035(20)

= .2 +.7 = .9 thousand = 900