(i) The factors of $$15$$ are $$1, 3, 5$$ and $$15$$
$$∴ F(15) = 1, 3, 5$$ and $$15$$
(ii) The factors of $$55$$ are $$1, 5, 11$$ and $$55$$
$$∴F(55) = 1, 5, 11$$ and $$55$$
(iii) The factors of $$48$$ are $$1, 2, 3, 4, 6, 8, 12, 16, 24$$ and $$48$$
$$∴F (48) = 1, 2, 3, 4, 6, 8, 12, 16, 24$$ and $$48$$
(iv) The factors of $$36$$ are $$1, 2, 3, 4, 6, 9, 12, 18$$ and $$36$$
$$∴F (36) = 1, 2, 3, 4, 6, 9, 12, 18$$ and $$36$$
(v) The factors of $$84$$ are $$1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42$$ and $$84$$
$$∴ F (84) = 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42$$ and $$84$$