I don't really understand the formula of doing the s question about indices...
I'm so confuse with the formula...
I hope someone can help me to understand it :)

Do you know what an index is?
Create one for yourself to understand the concept.

EXAMPLE:-

YEAR 2000 100
YEAR 2001 105
YEAR 2002 108
YEAR 2003 120
YEAR 2004 122
YEAR 2005 130
YEAR 2006 135
YEAR 2007 139
YEAR 2008 145
YEAR 2009 150

The formula as you call it is now simple to understand.

You can compare any year with any year .
EXAMPLE:-
All prices of the year 2000 have
Gone up 50% in the year 2009.
Please let me know what you do not understand.

Or are you talking about the powers in algebra?

Eg:
(ab)^5 = a^5b^5

:confused: