(i) ( 12, 16, 20, \ldots )
This is an arithmetic sequence with first term ( a = 12 ) and common difference ( d = 4 ).
Next four terms: [ \begin{align*} a_4 &= 20 + 4 = 24 \ a_5 &= 24 + 4 = 28 \ a_6 &= 28 + 4 = 32 \ a_7 &= 32 + 4 = 36 \end{align*} ]
Answer: ( 24, 28, 32, 36 )