Brantley and shawna walk to grandma's house at a rate of 4 mi/hr. they ride their bicycles back at 8mi/hr over the same route that they walked. it takes 1 hr longer to walk than to ride. how long did it take them to walk to grandma's?

the answers c

80π/3 or about 83.775

step-by-step explanation:

since a cone is 1/3 of a cylinder, we need to find the base's area. since area = πr^2, we get 16π. then, multiplying this by 5, we get 80π. dividing by 3, since the cone's volume is 1/3 of that of a cylinder's, we get 80π/3.

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