Mr. Jackson invested $800 at 6% per year and $ 2400 at 4 % per year
Solution:
Mr. Jackson invested a sum of money at 6% per year, and 3 times as much at 4% per year.
Let the sum invested be ‘a’ and ‘3a’ at 6% per year and 4 % per year respectively
Also, his annual return totaled $144
We can form following equation on the basis of question:-

a = $800
The amount of money invested at 6% = a = 800
The amount of money invested at 4 % = 3a = 3(800) = 2400
So, the amount of money invested at 6% is $800 and the amount of money invested at 4% is $ 2400