Answer:
$70,000.
Explanation:
The computation of the unredeemed coupons is shown below:
= Coupon value on 7/1/18 - 50% of Coupon value on 7/1/18 - Coupon value on 12/31/18
= $840,000 - 50% × $840,000 - $350,000
= $840,000 - $420,000 - $350,000
= $70,000
Only these dates should be considered in the computation part. The other dates which are mentioned in the question are not relevant hence, ignored it