John had 30,000 to invest. he invested part of his money and bonds paying 12 percent annual simple interest and the rest of the
money in a savings account giving 4% annual interest at the end of the year, he received $2400 as extra income how much money did John place in each investment?
Let the amount that John placed in bonds be . Then, the amount that he placed in the savings account has to be . Using those as the investment amounts, the total extra income is given by adding the two separate interests as shown:
We can now solve for x:
Thus, the amount that John put in each investment is