Answer:
$1,200
Explanation:
Let x be the amount of money deposited in the mutual fund. The interest earned by that investment can be determined as the amount deposited times the interest rate:

The value the second deposited can be determined as x+$2,400 and its interest earned is defined in the same manner as the first deposit's:

The total interest on both investment equals the sum of both interests:

$1,200 were invested in the mutual fund.