I'm trying to figure out how my science book is telling me to calculate this, can someone help me?

What is the acceleration of an object that takes 20 sec to change
from a speed of 200m/sec to 300 m/sec?
a. 5 m/sec.
b. 5 m/sec/sec.
c. 100 m/sec.
d. 100 m/ sec/sec.

Question

I'm trying to figure out how my science book is telling me to calculate this, can someone help me?

What is the acceleration of an object that takes 20 sec to change
    from a speed of 200m/sec to 300 m/sec?
    a. 5 m/sec.
    b. 5 m/sec/sec.
    c. 100 m/sec.
    d. 100 m/ sec/sec.

anonymous · Answer

@mossyfish  do you know anything on this subject? :)

anonymous · Answer

So, it took 20 seconds to change from 200m/sec to 300m/sec.  This is a difference of 100m/sec.  So, how much did it change each second?

anonymous · Answer

5?

anonymous · Answer

well that's simple. I'm so stupid sometimes. XD

anonymous · Answer

It's okay!  You didn't know the concept, that's all :)

anonymous · Answer

LOL people don't think i'm doing my homework. I am, but sometimes seeing the way the book writes it out just doesn't make sense to me.