Answer:Liza deposited $12000 at 1.5% and $24000 at 2.5%
Step-by-step explanation:
Let x represent the amount that she deposited at 1.5% interest.
Let y represent the amount that she deposited at 2.5% interest.
In planning her retirement, Liza deposits some money at 1.5% interest, with twice as much deposited at 2.5%. This means that
y = 2x
The formula for determining simple interest is expressed as
I = PRT/100
Considering the account paying 1.5% interest,
P = $x
T = 1 year
R = 1.5℅
I = (x × 1.5 × 1)/100 = 0.015x
Considering the account paying 2.5% interest,
P = $y
T = 1 year
R = 2.5℅
I = (y × 2.5 × 1)/100 = 0.025y
if the total annual interest income is $780 , it means that
0.015x + 0.025y = 780 - - - - - - - - - -1
Substituting y = 2x into equation 1, it becomes
0.015x + 0.025 × 2x = 780
0.015x + 0.05x = 780
0.065x = 78
x = 780/0.065
x = 12000
y = 2x = 12000 × 2
y = 24000
