Consider the arithmetic progression 7, 11, 15, … . Answer the following questions.
(i) Write the general expression for the nth term of this progression.
(ii) Describe the steps you would follow to decide whether 123 appears in the progression, and then carry out those steps.
(iii) If 123 is indeed a term, determine its position in the sequence. If it is not, give a reason based on your calculations.