In February, you have a balance of $270 in your bank account.In January, you have a balance of $270 - $45 = $225 in your bank account.In December, you have a balance of $225 - $45 = $180 in your bank account.
y = $180 + $45x, where x = 1, 2, 3, 4...
Balance in June: x = 6y = $180 + $45x = $180 + $45×6 = $180 + $270 = $450
