The "midpoint formula" is the same as the "average formula:"
x-coordinate of the midpoint = average of -2 and 10:
= (-2 + 10) / 2 = 4
y-coordinate of the midpoint = average of 3 and 3:
= (3+3) / 2 = 3
Thus, the midpoint of the given line segment is (4,3).
Three consecutive numbers can be written as x, x+1, and x+2, but they also can be written x, x-1, and x-2 where x is the biggest number.
sum means adding... so

combine like terms and solve for x!
If the scale factor is less then 1, it was reduced.
If the scale factor is more than 1, it was enlarged.
If it is equal to 1, it is the same.
Hope this helps!