Question 744436
The problem states

An investor invested a total of $1,800 in two mutual funds. One fund earned 9% profit while the other earned 3% profit. If the investor's total profit was $84, how much was invested in each mutual fund? 

let x = amount of money invested in 9% stock and
1800-x is amount of money invested in 3% stock

then we have

.09x + .03(1800 - x) = 84

.09x + 54 - .03x = 84

.06x = 30

x = 500

so $500  was invested at 9% and 
   $1300 was invested at 3%