Answer:
for 7% , $8,000
for 8.5%, $4,000
Step-by-step explanation:
Key amount at 7% be x and amount at 8.5% be y
Mathematically;
x + y = 12,000 ••••••(i)
Let’s now work
with the interest;
7% of x + 8.5% of y = 900 ••••••(ii)
0.07x + 0.085y = 900
So we have two equations to solve simultaneously
From 1, x = 12,000-y
Substitute this into ii
0.07(12000-y) + 0.085y = 900
840-0.07y + 0.085y = 900
0.015y = 900-840
0.015y = 60
y = 60/0.015
y = 4000
x = 12000-4000
x = $8,000
