Can some one explain this problem in detail for me ? (it's ap, algebra 1)

Indicate whether the scenario below is safe or unsafe: when storing a flammable liquid, you decide to separate it from other materials by a fire wall.

Facial shaving brushes are either bulb-shaped or fan-shaped. an experiment is to be conducted to determine whether the lather thickness is the same for both types of shaving brushes. in previous studies, it was determined that shaving brush size (small, medium, large) is associated with lather thickness, but shaving brush type (wolf whiskers, maggard razors, frank shaving, and so on) is not associated with lather thickness. how could the experiment best be conducted? by blocking on shaving brush size by blocking on shaving brush type by blocking on shaving brush shape by blocking on lather thickness without blocking

Free points + free ! if answered correctly which of these is not a good tip for passing? a. make sure you are on an area of road where it is legal and safe to pass. b. always drive at a safe speed at or below the speed limit. c. you may reduce your following distance below four seconds when passing. d. make sure there is a safe gap in traffic before you change lanes.