Water Co. leased machine from Air Co. on July 1, 2018 for an 8-year period expiring June 30, 2026. Equal payments under the lease are $60,000 and are due on July 1 of each year. The first payment was...

Water Co. leased machine from Air Co. on July 1, 2018 for an 8-year period expiring June 30, 2026. Equal payments under the lease are $60,000 and are due on July 1 of each year. The first payment was made on July 1, 2018. The rate of interest contemplated by Zinc and Helium is 10%. The cash selling price of the equipment is $352,000 and the cost of the equipment on Helium's accounting records is $280,000. The lease is appropriately recorded as sales-type lease.
What is the amount of interest revenue that Helium should record for the year ended December 31, 2018?