How is the CFA author calculating "Collection Days" in the bottom table below for the Weighted Average Collection period?

CFA Level I Corporate Finance
#1

I have put the following symbol next to the values I am confused about: “(???)”

Thanks.

**($ Millions)****January February March April Sales 530 450 560 680 Total accounts receivable 600 560 650 720 Current (1–30 days old) 330 290 360 280 1–30 days past due 90 120 160 250 31–60 days past due 80 60 60 110 61–90 days past due 70 50 40 50 >90 days past due 30 40 30 30 Aging Expressed as Percent January February March April Current (1–30 days old) 55.0 51.8 55.4 38.9 1–30 days past due 15.0 21.4 24.6 34.7 31–60 days past due 13.3 10.7 9.2 15.3 61–90 days past due 11.7 8.9 6.2 6.9 >90 days past due 5.0 7.1 4.6 4.2 Panel B: Calculation of the Weighted Average Collection Period March April Aging Group Collection Daysa****Weightb (%)****Weighted Daysc Collection Days Weight (%) **Weighted Days Current (1–30 days) 20 (???) 55.4 11.1 29 38.9 11.3 31–60 days 48 (???) 24.6 11.8 55 34.7 19.1 61–90 days 80 (???) 9.2 7.4 88 15.3 13.5 91–120 days 101 (???) 6.2 6.8 115 6.9 7.9 121+ days 130 (???) 4.6 6.0 145 4.2 6.1 Weighted average collection daysd 43.0 57.9

a The average days for collecting receivables in each grouping.

b The weighting from the aging schedule.

c This figure, expressed in days, is the product of the previous two columns.

d The sum of each grouping’s product equals the overall days.

#2

You can ignore this post. I’m not sure what happened to the formatting of the table, but it’s probably very confusing to look at.

I love this platform but it’s absolutely pathetic that you can’t delete a post

#3

You can try attaching an image of an Excel table.