the difference between the first two is 16

the difference between the second and third is 20

the difference between the third and fourth is 24

the difference between the fourth and fifth is 28

*notice how each difference differs by 4, adding each 4 for each successive difference

therefore, the difference between 108 and the next term will be 28+4, or 32

so 108+32 = 140

therefore, the next term in the sequence is 140