Let the amount that John placed in bonds be \(x\). Then, the amount that he placed in the savings account has to be \(\$30,000 - x\). Using those as the investment amounts, the total extra income is given by adding the two separate interests as shown:
\(.12x + .04(\$30,000 - x) = \$2,400\)
We can now solve for x:
\(.12x + .04(\$30,000 - x) = \$2,400\)
\(.12x + (\$1,200 - .04x) = \$2,400\)
\(.08x + \$1,200 = \$2,400\)
\(.08x = \$1,200\)
\(x = \$15,000\)
Thus, the amount that John put in each investment is
Bonds: \(x = \$15,000\)
Savings account: \(\$30,000 - x = \$30,000 - \$15,000 = \bf \$15,000\)
