Sara has six necklaces, but her mother will only allow her to wear two at a time. How many different combinations of two necklaces can Sara wear?

15
12
360
30

Abacteria population is tripling every hour. by what factor does the population change in 1/2 hour? select all that apply

Use the irregular polygon below. show all work. a. find the perimeter. b. find the area. the angles of the irregular polygon is 2, 8, 8, and 4.

Sound travels about 750 miles per hour. a) suppose it takes about 1.5 seconds to hear the echo. how far away is the canyon wall, in feet? for this i got 825 ft b) suppose you stand 1,925 feet from the canyon wall and sound the horn. how long will it take to hear the echo? (i'm stuck on this)