So in the first container it's just two date time tools and a select tool to change the sunrise and sunset times to the correct format and then change them into strings.
A formula tool was used to calculate the day length of each day in minutes.
The second container changes the columns back into numeric fields to change the format once more and remove the am and pm tags from the sunrise and sunset times.
A data cleanse tool was used to remove the initial row that was all null values.
A multi row formula was used to calculate the day length difference.
The next three formula tools were used to replace the first term with a zero in the day length difference column and change the formats of the sunrise and sunset columns so that the leading zeroes were removed, eg 06:28 became 6:28.
The final formula tool was used to replace the initial 0 in the day length difference column with a null so that it matched the output given in the solution.