Answer
Wade's homeowner's insurance costs $650 a year.
Since his first payment is $140, then the amount remaining after the first payment will be $650 - $140 = $510.
If each payment is 20% of what he owes after the first payment, this implies that his second payment will be

The second payment will be $102
The amount remaining after the second payment will be $510 - $102 = $408
Now, to know the next remaining payment, we have to calculate the ratio of the amount remaining after the first and the second payment, that is

Therefore, we shall generate the next remaining payment by multiplying the previous remaining payment by 1.25. This yields the sequence below
$510, $408, $326.4, $261, $208.896, $167.1168....................$1.541