To solve the equation, we need to isolate the variable x.

First, let's simplify the equation by performing the operations inside the parentheses:

315 + (125 - x) = 426

Combine like terms inside the parentheses:

315 + 125 - x = 426

Combine like terms on the left side:

440 - x = 426

Next, let's isolate the variable x by subtracting 440 from both sides:

440 - x - 440 = 426 - 440

Simplify:

-x = -14

To solve for x, we need to isolate it by multiplying both sides by -1:

(-1)(-x) = (-1)(-14)

Simplify:

x = 14

Therefore, the solution to the equation is x = 14.