.43 - (j + .1) - (4.2 + .51) - j

To solve this expression, we can simplify it step-by-step:

1) Distribute the negative sign to each term within parentheses:
.43 - j - .1 - 4.2 - .51 - j

2) Combine like terms:
(.43 - .1 - 4.2 - .51) - (j + j)

3) Simplify the numbers:
(-3.38) - (2j)

Therefore, the simplified expression is -3.38 - 2j.