To solve for the missing expression, we need to isolate the variable x on one side of the equation.
We can start by multiplying both sides of the equation by the reciprocal of 2/3, which is 3/2, to get rid of the fraction:
```
2/3 ( ) = -5 + 4x
(3/2) * 2/3 ( ) = (3/2) * (-5 + 4x)
( ) = -15/2 + 6x
```
Now we can compare this expression to the possible answer choices to see which one makes the equation true:
A: -15/2 + 6X --> This is the same expression we just solved for, so it must be the correct answer.
B: 10/3 + 8/3X --> This expression does not match our solution.
C: 5 2/3+3 1/3X --> This expression does not match our solution.
D: -15+12X --> This expression does not match our solution.
Therefore, the answer is A: -15/2 + 6X.