SOLUTION: A person invested $9000, part at 4 1/2%p.a and the rest at 5% p.a. If the total interest he earned after one year was $435, find the amount of each investment?

Question 949329: A person invested $9000, part at 4 1/2%p.a and the rest at 5% p.a. If the total interest he earned after one year was $435, find the amount of each investment?
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
x=invested at 4.5%; y=invested at 5%;
x+y=$9000 Subtract y from each side
x=$9000-y
0.045x+0.05y=$435 Substitute for x.
0.045($9000-y)+0.05y=$435
0.045($9000)-0.045y+0.05y=$435
$405+0.005y=$435 subtract $405 from each side.
0.005y=$30 Divide each side by 0.005
y=$6000 ANSWER 1:$6000 was invested at 5%.
x=$9000-y=$9000-$6000=$3000 ANSWER 2: $3000 was invested at 4.5%.
CHECK
0.045x+0.05y=$435
0.045($3000)+0.05($6000)=$435
$135+$300=$435
$435=$435

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