The following patents were on Presto's balance sheet as of December 31, 2018.

PATENT ITEM

INITIAL COST

DATE ACQUIRED

USEFUL LIFE AT DATE ACQUIRED

Patent 421

$30,600

3/1/15

17 years

Patent 183

$20,000

7/1/16

10 years

Patent 709

$15,500

9/1/18

5 years

In 2019, Presto had the following occur:

• Research and development costs of $245,700 were incurred during the year.
• Patent 820 was purchased on July 1, 2019 for $37,480. This patent was recorded as having a useful life of 9 years.

What is the carrying amount of Presto's patents on December 31, 2019?