You can solve this using a system of equations:
0.06x + 0.08y = 2060 (interest)
x + y = 29,000 (money invested)
Multiply each term in the second equation by -0.06 to cancel out the 0.06x from the first equation.
-0.06x - 0.06y = -1740
Now add this equation to the first equation and solve for y.
0.06x + 0.08y = 2060
-0.06x - 0.06y = -1740
0.02y = 320
y = 16,000
Since you know y = 16,000 you can substitute it into either of the original equations to solve for x. I picked the second equation because it's simpler, but you could also use the first.
x + 16,000 = 29,000
x = 13,000
So you invested 16,000 at 8% and 13,000 at 6%.
