(a)

+	1	3	5
2	3	5	7
3	4	6	8
4	5	7	9

Sample space = 9
Sum greater than 3 but less than 7 = {5, 4, 6, 5} = 4
P(sum greater than 3 but less than 7) = \(\frac{4}{9}\).
(b) Given that y + m = 90°
< ABE = x° (vertically opp. angles)
< BAD = (x + m)° (exterior angles)
< DCB = (x + y)° (exterior angles)
(x + m)° + (x + y)° = 180° (opp. angles of a cyclic quadrilateral)
(2x + y + m)° = 180°
(2x + 90) = 180
2x = 180 - 90 = 90°
x = 45°