Kylie starts with $145 in her piggy bank. Each month she adds $20. Which recursive function rule models the total amount in Kylie’s piggy bank at the end of each month?

an=20⋅an−1 and a1=145

an=145⋅an−1 and a1=20

an=20+an−1 and a1=145

an=145+an−1 and a1=20