Calculate the net worth of Sharon Williams, based on her assets and liabilities: Sharon owns a car worth $25,000; but she still owes $10,000 on the car loan. She rents an apartment and her most valuable possession is her grandmother's wedding ring that was recently appraised at a value of $2,000. Her liabilities are the outstanding amonunt she owes on her car, $1,000 in credit card debt, and a $5,000 loan her aunt gave her that she needs to pay back. What is Sharon's net worth?