Don and Petra are residents of Puerto Rico who use the Married Filing Jointly status. Their income consists of:

• $30,000 wages from the Puerto Rico Water Authority
• $2,000 interest paid by Banco Popular (a Puerto Rican bank)
• $18,000 retirement benefits paid by the Social Security Administration
• $5,000 rental income from property in San Juan, Puerto Rico

Based on this information, Don and Petra's total U.S. source income is: $ (Please do not use commas in answer)