To solve for x, first simplify the equation:

21.87 - (313 / x + 8.74) = 12.93
21.87 - 313 / x - 8.74 = 12.93
21.87 - 8.74 = 313 / x + 12.93
13.13 = 313 / x + 12.93

Next, isolate the term with x by subtracting 12.93 from both sides:

13.13 - 12.93 = 313 / x
0.2 = 313 / x

Now, multiply both sides by x to solve for x:

0.2 * x = 313
x = 313 / 0.2
x = 1565

Therefore, the solution to the equation is x = 1565.