Refer to figure.
During the calculation of the CG location (right hand side of the load/trim sheet), you must start at the dry operating index of 51, then go down to each line and make the suitable correction for that section, which, in this case, leads us to leave the usable area (then re-enter later). This can be approached two ways, either by making ruler measurements and continuing using the same scale outside of the charted area, or by skipping a row in order to get closer to the centre, then returning to that skipped row later on, and this allows us to stay on the charted area always, with no change in answer. The video shows the first method, but be aware that the second method is the only realistic method to use if the line goes too far out of the area. In this question, either method works fine.

Once we have the trim index value, we must identify the takeoff mass:

Takeoff mass = DOM + takeoff fuel + traffic load = 59 800 kg. Draw this line horizontally in the mass/balance envelope.

We can then go down from the trim index until we intercept the takeoff mass line we have already drawn.

CG at takeoff = 18% (approx. 18.3%)