Question

@eashy @ganeshie8 @shamil98

Answer 1

common difference = t[n+1]-t[n]
t[0]=-6
t[1]=-2
t[2]=2
t[3]=6
t[4]=10

Answer 2

Just subtract T_1 - T_0 to get the common difference.
-2 - (-6) = 4
There is your common difference.