Paul has $30,000 to invest. his intent is to earn 15% interest on his investment. he can invest part of his money at 8% interest and part at 18% interest. how much does paul eed to invest in each option to make a total 15% return on his $30,000?
a) 6% interest
b) 15% interest

Amount invested at 8% is $9000 and amount invested at 18% is $21000.

Step-by-step explanation:

Let amount invested at 8% be x.

Let amount invested at 18% be y.

We get the 1st equation as:

      ........(1)

We get the second equation as:

=>

or getting rid of the decimal by multiplying by 100 on both sides.

         ........(2)

Multiplying (1) by 8 and subtracting from (2) we get

So, y = 21000

And

So, x = 9000

Therefore, amount invested at 8% is $9000 and amount invested at 18% is $21000.