Question

Q8 Q21.) Find the amount invested at each rate.

Answer 1

See the attached picture:

6% = 1200
9% = 2400
12% = 3800

Answer 2

Let x, y, z be the amount at 6%, 9% n 12%

x+y+z = 7400
z-x-y = 200
2z = 7400+200 = 7600
z = 3800

@12%, 3800 gives 3800*0.12=456 income
0.06x+0.09y+456=744
0.06x+0.09y=288
6x+9y=28800

x+y+3800=7400
y=3600-x

6x+9(3600-x)=28800
9x-6x=9*3600-28800=3600
x=1200

y=3600-1200
=2400