I would add, the weight of the backpack and the weight of the school books which is 28.36.
So Rico's backpack altogether weighs 28.36.
I'm pretty sure.
Answer:

Step-by-step explanation:
The formula for the amount accrued on an investment earning compound interest is

where
P = the amount of money invested
r = the interest rate per payment period expressed as a decimal fraction
t = the number of periods
Your formula is

Is there a picture for it?