Answer:
B: leaving metal outside in the rain until rust forms an it's surface
Their average velocity is 0.98 m/s east.
Explanation:
The average velocity of an object is defined as the ratio between the displacement and the time taken:

The displacement is a vector connecting the initial point to the final point of motion: so, being displacement a vector, velocity is a vector as well, having the same direction of displacement.
Here, Heather and Matt walk 2.0 km eastward, so their displacement is
d = 2.0 km = 2000 m (east)
While the time they took is

Therefore, their average velocity is

And the direction is the same as the displacement (east).
Learn more about average velocity:
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<span>They are balanced. If the forces were not balanced the book would move*. In this example, the downward force of gravity on the book is counterbalanced by the upthrust of the desk. </span>
Answer:
a) 15 b) 60 i think is the answer