What is the LS LF and slack and explain how you got the answers

CRITICAL PATH TASK ES EF LS LF SLACK 01- Develop Plan 2 02- Assign Tasks 2 5 03- Obtain Hardware 2 18 04- Programming 6 75 05- Install Hardware 19 28 06- Program Test 76 105 07- Write User Manual 29 53 08- Convert Files 29 48 09- System Test 54 106 73 130 106 130 10- User Training 106 130 106 130 OO 11- User Test 131 155 131 155 PATHS Path A: 1-2-4-6-9-11 - 155 CRITICAL Path B: 1-3-5-7-10-11 - 98 Path C: 1-3-5-8-10-11 -93