Help with highlighted red answers.. do not know why there are wrong

For each of the problems listed, determine the following quantities for each activity: the earliest start time, latest start time, earliest finish time, latest finish time, and slack time. List the critical activities, and determine the expected duration of the project. a. Activity-on-arrow diagram 5 10 8 8 10 (12 ) 11 Answer is complete but not entirely correct. ES EF LS LF Slack Summary: Activity 1-2 1-3 0 4 7 7 11 21 X 4 X 13 X 12 X 8 X 2-4 13 x 18 x 21 x 26 X 8 2-5 18 X 20 X 26 X 28 x 8 X 3-6 21 x 24 x 28 X 31 x 7 X 7 7 X 7 4-7 4 X 12 x 19 X 11 X 19 5-8 12 19 26 7 6-9 19 X 21 x 26 X 28 X 7 X 7-10 0 x 10 X 0 X X 10 X 0 10 X 16 X 0 8-10 9-11 10X 16 X 16 x 20 x 16 20 X 25 X 0 20 X 25 x 20 X 0 X 10-12 11-12 25 31 25 31 0