They have asked for an average track and, strictly speaking, it should be measured at the mid-point.  

However, this is a relatively short and predominantly North/South track so there will be very little difference between the initial and mean track.  

Having drawn the line from CRK to CRN put the protractor over CRK and align it with magnetic North (the 053ēM and 353ēM radials on the chart will help with this alignment).  

Note the track CRK-CRN is 357ēM.  

With compasses/dividers measure the distance CRK-CRN using the latitude scale: 89 NM.           

Alternatively, go for the application of common sense and note that the track is a bit more than 353ēM (CRK-SHA) and there is only one feasible option.