$($a$)$ Given the following information:

$\backslash$table$[[$Task$,\backslash$table$[[$Immediate$],[$Predecessor$]],\backslash$table$[[$Task time$],[($Mins$)]]],[A,-,12],[B,A,6],[C,B,6],[D,B,2],[E,B,2],[F,B,12],[G,C,D,7],[H,G,5],[I,E,1],[J,$I,$F,4],[K,H,J,6],[L,K,7]]$

Calculate :

$($i$)$ Theoretical minimum number of workstations required to balance the line

Vii$)$ Balance the line using the LOI rule, and assuming $12$ minutes per workstation

$($iii$)$ Calculate the efficiency of the line.