Answer:
$307.5.
Step-by-step explanation:
We have been given that Elena's aunt bought her a $150 savings bond when she was born.When Elena is 20 years old, the bond will have earned 105% in interest.
To find bond's value after 20 years we will add 105% of 150 to 150.




Therefore, the bond will be worth $307.5, when Elena will be 20 years old.