Question 656804
Solution: 
we have given 

8000*7% + x* 9% = 1550
so, 8000*7/100 + x* 9/100 = 1550
=> 80*7 + x(0.09) = 1550
=> 560 + x(0.09) = 1550
=> x(0.09) = 1550 - 560
=> x = 990/0.09
     = $11000

Hope this will help you!