Answer: 18
Reason:
Subtract any pair of adjacent terms
- d = term2 - term1 = -74 - (-92) = -74+92 = 18
- d = term3 - term2 = -56- (-74) = -56+74= 18
- d = term4 - term3 = -38- (-56) = -38+56= 18
- d = term5 - term4 = -20- (-38) = -20+38= 18
Each time we get the same value to confirm that we have an arithmetic sequence of common difference 18.