Expanding the bracket:

5x − 2(x − 5) = 4x

5x − 2x + 10 = 4x

3x + 10 = 4x

Subtracting 3x from both sides and swapping sides gives:

x = 10

CHECK:

LHS = 5 × 10 − 2(10 − 5) = 50 − 10 = 40

RHS = 4 × 10 = 40 = LHS.

Checks OK.