Question 153650
Let x be the amount invested in funds that earned 8%.
Then the amount invested in stock that suffered 3% loss is 18,000 - x.
The profit from investment in funds is 8%x
The loss from investment in stock is 3%(18,000 - x).
The net profit is 8%x - 3%(18,000 - x).
As the net profit given in the problem is $780, we have:
8%x - 3%(18,000 - x) = 780
Solving for x, we have:
8x - 3(18,000 - x) = 78000   (multiply both sides by 100)
8x - 54000 + 3x = 78000
11x = 132000
x = 132000/11
x = 12,000
So 
the amount invested in funds that earned 8% is 12,000.
the amount invested in stock that suffered 3% loss is 18,000 - x = 18000 - 12000 = 6,000.