Use the following problem statement to answer questions $23-25.$

The project network below shows activity times $($in weeks$)$ and their precedence

relationships. $[$Note$]$ ES $=$ Maximum $($EF$).$ EF $=$ ES $+$ t$.$ LF $=$ Minimum $($LS$).$ LS $=$ LF $-$ t$.$ Sla

LS $-$ ES$.$ Slack $=$ LF $-$ EF$.$

Question $23$

What is the EF time for activity E$?$

Question $24$

What is the LS time for activity E$?$

Question $25$

What is the slack time for activity $C?$