Question 88287
You seem to have TWO errors in your second step!

0.14x+0.13(20,000-x)=2,720
0.14x+2,800-.013x=2,720


Should be 
0.14x+0.13(20,000-x)=2,720
0.14x+2,600-0.13x=2,720


Continuing:
0.01x = 120
x= $12000
20000-x = $8000


Check:  .14(12000)+.13(8000)=2720


R^2