Exponents question

[rmyoungsc]

If 5^21 * 4^11 = 2 * 10^n, what is the value of n?

a) 11
b) 21
c) 22
d) 23
e) 32

the answer is b)

I can't figure out how to do this one.

help please!

[Ben Ku]

Hi,

Please see the solution on this post:

http://www.manhattangmat.com/forums/5-21-x-4-11-2-x-10-n-t7549.html

Let me know if you have any additional questions!