Fred receives the following on an installment sale of real estate. He sold the property in 2020 for $100,000, receiving $30,000 cash and an agreement from the buyer to pay $50,000 in installments with the first payment due February 1, 2021. At the time he sold the property, Fred owed $20,000 on a mortgage for which the buyer agreed to become liable (assume). If Fred's basis in the property is $60,000, what is Fred's taxable gain under the installment method for the year of the sale (show your work).