a) {5, 7, 35};   b) {1, 2, 4, 5, 7, 8};   c) {3, 5, 7, 9};
d) ]0, 10]  U {14, 20, 28, 35, 40, 56, 70, 140, 280};   e) {1, 2, 3, 4, 5, 7, 8, 9};   f) {1, 2, 4, 5, 7, 8, 35}.