please help these 2 questions.

29. Suppose we define [a]is = (a + 13 : ne Z) Then define Z13 = {[1]13. [2)13, [3]13. .... [12]13} and suppose we define multipli- cation as [ahis . [b/13 = [a . bis Find the multiplicative inverse of [8]is (type the number only no strange brackets, spaces or symbols) 30. Suppose we define [ale = {a + n67 : n E Z} Then define Z67 = {[1 67. [2)67, [3)67,.... [66]67} and suppose we define multipli- cation as [a]67 . [6)67 = [a . be7 Find the multiplicative inverse of [48]67 (type the number only no strange brackets, spaces or symbols)