Word problem involving pre-algebra

Question

Julia's text messaging plan charges 15¢ for each message over 300 in addition to a $7 base charge. If she owes $15.10 for text messaging in the month of June, how many text messages did she send that month?

Answer 1

$15.10-$7.00=$8.10 owed for text messages

8.1/0.15=54 text messages paid for over 300

she sent 300+54=354 text messages