If we let x represent the total number of copies sold to date, then we can find 9.6% of the missing number x that is equal to 36200.
For example, 20% of 10 is 2
This can be calculated by multiplying the percent in decimal form by the total number of "items":
0.20 * 10 = 2
For your problem, 9.6% in decimal form is 0.096:
0.096 * x = 36200
If you divide 36200 by 0.096, you will determine the total of copies sold to date: 36200 / 0.096 = 377083 copies
To verify: 0.096 * 377083 = 36200