The amount he add to his account is $300 to buy 20 weeks worth of tickets.
It is required to find the amount he add to his account.
What is arithmetic?
Arithmetic is the branch of mathematics that deals with the study of numbers using various operations on them. Basic operations of math are addition, subtraction, multiplication and division. These operations are denoted by the given symbols.
Given:
He paid $15 per ticket, once a week, so:
240 / 15 = 16
The commuter bought tickets for 16 weeks.
If he wants 20 weeks' worth of tickets, he must pay $15 for each ticket,
so 20 x 15 = $300.
Therefore, the amount he add to his account is $300 to buy 20 weeks worth of tickets.