A car travels 40 miles north in 30 minutes and then turns around and travels 20 miles south in 30 minutes. What is the cars average speed in miles/hour?

this is poiselle's equation from fluid mechanic in physics. mech eng

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2