Smith, a divorced person, provided over one-half the support for his widowed mother, ruth, and his son, clay, both of whom are u. s. citizens. during this year, ruth did not live with smith. she received $9,000 in social security benefits—none of which was taxable. clay, a full-time graduate student, and his wife lived with smith. clay had no income but filed a joint return, owing an additional $500 in taxes on his wife's income. how many exemptions was smith entitled to claim on his tax return?