Question 352026
You can define a variable.


Let x be the sum invested at 9% interest.



(30000-x) will be the sum invested at 14% interest.



The interest in the first case becomes: 9



The interest in the second case becomes: (30000 - x) times 14.



Total interest = (9x/100) + 14(3000 - x)/100



Now, equate to 3000 to find the value of x, the amount invested to 9% interest.



(9x/100) + 14(3000 - x)/100 = 3000



This gives you the greatest value invested at 9% interest to get 3000 interest per year.


If less is invested at 9%, more will be invested at 14% and you get a higher interest.



Ideally, if you want to make the most interest, put everything at 19 percent.