Answer: 
Step-by-step explanation:
The interest (simple interest)
is calculated by:

Where:
is the principal
is the percent of the principal that is paid over a period of time (yearly in this case).
is the time, since we are told the money was left in the account for 9 months of the 12 months a year has.


Answer:
6
Step-by-step explanation:
It is C. Associative property of multiplication