There are 3x-2 trees planted in each row of a rectangular parcel of land. if there are a total of 24x-16 trees planted and the parcel, how many rows of trees are there in the parcel?

Let's call the number of rows 'R' . (Clever ?)

There are (3x -2) trees in each row, and there are 'R' rows,
so the total number of trees is [ R times (3x-2) ].

But the problem told you that the total number of trees is (24x-16).
So
       R(3x - 2) = (24x - 16)

For a quick, happy ending, how about factoring '8' out of the right side:

       R(3x - 2) = 8(3x - 2)

Is it jumping out at you yet ?
If not, then divide each side by (3x - 2) :

       R      =      8

There are eight (8) rows of trees.

24 is the correct answer.