According to Section
5-36 of the manual, on a meridional line the latitude of the
closing distance will be distributed along the measurement of each
course in proportion to its own difference in latitude, and then
each temporary stake will be set over to the east or to the west
for the departure of the closing distance in proportion to the total
distance from the starting point.

In other words, on an irregular line, adjustments in the direction
of the line whether latitudinal or meridional are done just like
single-proportion, while adjustments perpendicular to the direction
of the line are done according to the Bowdich Method, or more commonly
referred as the Compass Rule.

So, in this problem, we would distribute the latitude of the closing
error using the single proportionate ratio.

The latitude of the closing error is to the sum of the record latitudes
as the adjustment to each course's latitude is to the accumulated
record latitude of that course, or A1 is to A as B1 is to B in the
drawing.