My little sister, Savannah, is three years old and has a piggy bank
that she wants to fill. She started with five pennies and each day when I come home
from school, she is excited when I give her three pennies that are left over from my
lunch money. How much money will Savannah have after 10 days? How many days
will it take for her to have at least $1.50? Justify your answer with a mathematical
model of the problem situation.