Question 282214
Mardi received an inheritance of $70,000. She invested part at 10% and deposited the remainder in tax-free bonds at 8%. Her total annual income from the investments was $6800. Find the amount invested at 10%.

Let Mardi invest $ x at 10%
And $y at 8%

x+y=70000 ---------------1

The sum of interest from each investment = 6800

0.1x+0.08y=6800----------2

Multiply equation 2 by 10

x+0.8y=68000 .----------3

x+0.8y -(x+y)= 68000-70000

x+0.8y-x-y= -2000

-0.2y=-2000

y= 2000/-0.2

y=10000

If y =10000 
then x= 60000 investment in 10% bonds