To solve this expression, we need to follow the order of operations (PEMDAS).

1. First, simplify the addition and subtraction of fractions:
1/2 - 3/4 + (-1/2) + 2/3 - 1/2
= 1/2 - 3/4 - 1/2 + 2/3 - 1/2
= 1/2 - 1/2 - 3/4 + 2/3 - 1/2
= 0 - 3/4 + 2/3 - 1/2
= -3/4 + 2/3 - 1/2

2. Find a common denominator for the fractions:
The common denominator for 4, 3, and 2 is 12.

-3/4 = -9/12
2/3 = 8/12
-1/2 = -6/12

So, the expression becomes:
-9/12 + 8/12 - 6/12

3. Add and subtract the fractions:
-9/12 + 8/12 - 6/12
= (-9 + 8 - 6) / 12
= -7/12

Therefore, the simplified expression is -7/12.