SOLUTION STEPS:
  1. Split the decimal: 1.8 = 1 + 0.8. Write 0.8 as a fraction: 8/10.
  2. Simplify 8/10: divide top and bottom by 2 to get 4/5.
  3. So 1.8 = 1 4/5. Match option (1): 1 4/5.