Here's some hiints/comments:

For 8.24, drawing a diagram is necessary, just be careful with the requirements. As a note to clarify, Jack will not wait after 5:45 means he definitely will not wait after 5:45 (even if he he started waiting at 5:43, he'll stop at 5:45). The region might be a little confusing, but it should be all straight lines, so areas can be calculated with triangles, parallelograms, etc.

For 8.28, let's consider a simpler question, what are all the points that are a distance of less than 1 from (0,0). Well the points of exactly distance one form a circle of radius 1, so points of distance less than 1 are all the points inside this circle. This type of reasoning will be needed for 8.28 because we're talking about distances from vertices.

For 8.29 we're picking 4 balls, so there should be (18 choose 4) total outcomes. The "Be careful here" hint is meant to make clear we need to consider some different cases to get at least one of each color.