What is the structure of the following sentence? We looked for seashells on the beach, but we did not find any sand dollars. compound simple complex compound-complex

The second term of an arithmetic sequence is 30. the fifth term is 90.calculatei). the commor difference of the sequence ii). the first term of the sequence tje first, second and fifth terms of the arithmetic sequence are the first three terms of a geometric sequence calculate the seventh term of the geometric sequence