To get the percent of decrease in the cost of season tickets, first, subtract the original cost to the current cost.
$1620 - $1537.38 = $82.62
Next, divide it to the original cost of the ticket, and multiply by 100%
$82.62 ÷ $1620 = 0.051
0.051 × 100% = 5.1%
Therefore, the percent of decrease in the cost is 5.1%.