Question 943739
One approach is to look at the differences between terms:


12, 17, 27, 47


Then the differences between terms of the previous sequence:


5, 10, 20


We can try assigning 40 as the next term in the above sequence (since it appears to double), so the difference in the first sequence would be 47+40 = 87. By this rule, the next term would be 109+87 = 196.


There are probably other approaches that give different answers, which is why these sequence problems usually aren't very good.