3) 1 + (1/3 - 1/5) / (1/3 + 1/5)

1/3 - 1/5 = (5-3)/15 = 2/15. 1/3 + 1/5 = (5+3)/15 = 8/15. (2/15) / (8/15) = 2/8 = 1/4. 1 + 1/4 = 5/4.
Answer: 5/4