15,17,19 thats easy just keep adding two if you want to predict the next numbers
84= 7(6+a)
84= 42 +7a
84-42= 42-42 +7a
42= 7a
42/7= 7a/7
6= a
-84= -6( p+6)
-84= -6p -36
-84+36= -6p -36+36
-48= -6p
-48/-6= -6p/-6
8 =p
Answer:
C
Step-by-step explanation:
D is a geometric sequence.