Please help me. Thanks.

All questions refer to the following game. Player 1 is Sick (S) with probability a and Healthy (H) with probability 1 a. He chooses whether to wear a mask (m) or not (11). Player 2 decides whether to avoid l (A) or not (N). Player 1 doesn't like to be avoided, and wearing a mask is costly for him. Player 2 prefers to avoid a sick Player 1, especially if he's not wearing a mask. The extensive form is as follows: -0.25,0 \\g A// 0.0 \\\\ 0.75,-1 N \\1,-2 -0.25,0 \\ A /0,0 / 0.75,1 N\\\\1,1 Suppose that a