To solve the equation |-x + 2/5| + 1/2 = 3.5, you can follow these steps:

Step 1: Subtract 1/2 from both sides of the equation to isolate the absolute value term:
|-x + 2/5| = 3.5 - 1/2

Step 2: Simplify the right side of the equation:
|-x + 2/5| = 7/2 - 1/2
|-x + 2/5| = 6/2
|-x + 2/5| = 3

Step 3: Split the equation into two cases, one for when -x + 2/5 is positive and one for when it is negative:
Case 1: -x + 2/5 ≥ 0
Case 2: -x + 2/5 < 0

Step 4: Solve each case separately:
Case 1: -x + 2/5 ≥ 0
Solve for x:
-x + 2/5 ≥ 0
-x ≥ -2/5
x ≤ 2/5

Case 2: -x + 2/5 < 0
Solve for x:
-x + 2/5 < 0
-x < -2/5
x > 2/5

Step 5: Combine the solutions from both cases:
The solution to the equation |-x + 2/5| + 1/2 = 3.5 is x ≤ 2/5 or x > 2/5.