Explanation

9000 + 16 2/3% of x = 10500

By converting the percentage to a fraction:

50/3 % = 50/(3*100) = 1/6

So, the equation becomes:

9000 + (1/6)x = 10500

Subtracting 9000 from both sides:

(1/6)x = 1500

Multiplying both sides by 6:

x = 1500*6

x = 9000